Add contribution veto function

Allows anybody with the VETO_CONTRIBUTION_ROLE to veto a contribution
and thus prevent that the contribution can be claimed.
So far like the ADD_CONTRIBUTION_ROLE any contributor is allowed to
veto.

apps/contribution/arapp.json

@@ -9,6 +9,11 @@
       "name": "Manage token contract",
       "id": "MANAGE_TOKEN_CONTRACT_ROLE",
       "params": []
+    },
+    {
+      "name": "Veto contributions",
+      "id": "VETO_CONTRIBUTION_ROLE",
+      "params": []
     }
   ],
   "environments": {

apps/contribution/contracts/Contribution.sol

@@ -9,6 +9,7 @@ interface IToken {
 
 contract Contribution is AragonApp {
   bytes32 public constant ADD_CONTRIBUTION_ROLE = keccak256("ADD_CONTRIBUTION_ROLE");
+  bytes32 public constant VETO_CONTRIBUTION_ROLE = keccak256("VETO_CONTRIBUTION_ROLE");
 
   bytes32 public constant KERNEL_APP_ADDR_NAMESPACE = 0xd6f028ca0e8edb4a8c9757ca4fdccab25fa1e0317da1188108f7d2dee14902fb;
   // ensure alphabetic order
@@ -24,6 +25,7 @@ contract Contribution is AragonApp {
     uint8 hashSize;
     string tokenMetadataURL;
     uint claimAfterBlock;
+    bool vetoed;
     bool exists;
   }
   string internal name_;
@@ -39,6 +41,7 @@ contract Contribution is AragonApp {
 
   event ContributionAdded(uint256 id, address indexed contributor, uint256 amount);
   event ContributionClaimed(uint256 id, address indexed contributor, uint256 amount);
+  event ContributionVetoed(uint256 id, address vetoedByAccount);
 
   function initialize(bytes32[4] _appIds) public onlyInit {
     appIds = _appIds;
@@ -77,7 +80,7 @@ contract Contribution is AragonApp {
     return contributions[contributionId].tokenMetadataURL;
   }
 
-  function getContribution(uint256 contributionId) public view returns (uint256 id, address contributor, uint256 amount, bool claimed, bytes32 hashDigest, uint8 hashFunction, uint8 hashSize, uint claimAfterBlock, bool exists) {
+  function getContribution(uint256 contributionId) public view returns (uint256 id, address contributor, uint256 amount, bool claimed, bytes32 hashDigest, uint8 hashFunction, uint8 hashSize, uint claimAfterBlock, bool exists, bool vetoed) {
     id = contributionId;
     ContributionData storage c = contributions[id];
     return (
@@ -89,7 +92,8 @@ contract Contribution is AragonApp {
       c.hashFunction,
       c.hashSize,
       c.claimAfterBlock,
-      c.exists
+      c.exists,
+      c.vetoed
     );
   }
 
@@ -114,10 +118,20 @@ contract Contribution is AragonApp {
     emit ContributionAdded(contributionId, contributorAccount, amount);
   }
 
+  function veto(uint256 contributionId) public isInitialized auth(VETO_CONTRIBUTION_ROLE) {
+    ContributionData storage c = contributions[contributionId];
+    require(c.exists, 'NOT_FOUND');
+    require(!c.claimed, 'ALREADY_CLAIMED');
+    c.vetoed = true;
+
+    emit ContributionVetoed(contributionId, msg.sender);
+  }
+
   function claim(uint256 contributionId) public isInitialized {
     ContributionData storage c = contributions[contributionId];
     require(c.exists, 'NOT_FOUND');
     require(!c.claimed, 'ALREADY_CLAIMED');
+    require(!c.vetoed, 'VETOED');
     require(block.number > c.claimAfterBlock, 'NOT_CLAIMABLE');
 
     c.claimed = true;

arapp.json

@@ -5,6 +5,11 @@
       "id": "ADD_CONTRIBUTION_ROLE",
       "params": []
     },
+    {
+      "name": "Veto contributions",
+      "id": "VETO_CONTRIBUTION_ROLE",
+      "params": []
+    },
     {
       "name": "Manage contributors",
       "id": "MANAGE_CONTRIBUTORS_ROLE",

contracts/KreditsKit.sol

@@ -45,11 +45,13 @@ contract KreditsKit is KitBase  {
         proposal.initialize(appIds);
 
         acl.createPermission(root, contribution, contribution.ADD_CONTRIBUTION_ROLE(), this);
+        acl.createPermission(root, contribution, contribution.VETO_CONTRIBUTION_ROLE(), this);
         acl.grantPermission(proposal, contribution, contribution.ADD_CONTRIBUTION_ROLE());
         
         uint256[] memory params = new uint256[](1);
         params[0] = uint256(203) << 248 | uint256(1) << 240 | uint240(contributor);
         acl.grantPermissionP(root, contribution, contribution.ADD_CONTRIBUTION_ROLE(), params);
+        acl.grantPermissionP(root, contribution, contribution.VETO_CONTRIBUTION_ROLE(), params);
 
         //acl.setPermissionManager(this, proposal, proposal.VOTE_PROPOSAL_ROLE();
         acl.createPermission(root, proposal, proposal.VOTE_PROPOSAL_ROLE(), this);
@@ -61,6 +63,7 @@ contract KreditsKit is KitBase  {
         acl.setPermissionManager(root, proposal, proposal.VOTE_PROPOSAL_ROLE());
         acl.setPermissionManager(root, proposal, proposal.ADD_PROPOSAL_ROLE());
         acl.setPermissionManager(root, contribution, contribution.ADD_CONTRIBUTION_ROLE());
+        acl.setPermissionManager(root, contribution, contribution.VETO_CONTRIBUTION_ROLE());
         
         acl.createPermission(root, token, token.MINT_TOKEN_ROLE(), this);
         acl.grantPermission(contribution, token, token.MINT_TOKEN_ROLE());