Add ACL contract wrapper

this mainly allows us to check if an account has a certain role and thus
if the account can call specific contract functions.

At some point we might want to extend that to support the check if an
account can call the function. For that we would need to have a mapping
between function names and roles, which we have not right now.

lib/contracts/acl.js

@@ -0,0 +1,13 @@
+const Base = require('./base');
+const EthersUtils = require('ethers').utils;
+
+class Acl extends Base {
+
+  hasPermission(fromAddress, contractAddress, roleID, params = null) {
+    let roleHash = EthersUtils.keccak256(EthersUtils.toUtf8Bytes(roleID));
+    console.log(roleHash)
+    return this.functions.hasPermission(fromAddress, contractAddress, roleHash, params);
+  }
+}
+
+module.exports = Acl;

lib/contracts/index.js

@@ -3,5 +3,6 @@ module.exports = {
   Contribution: require('./contribution'),
   Proposal: require('./proposal'),
   Token: require('./token'),
-  Kernel: require('./kernel')
+  Kernel: require('./kernel'),
+  Acl: require('./acl')
 };

lib/contracts/kernel.js

@@ -5,6 +5,9 @@ KERNEL_APP_ADDR_NAMESPACE = '0xd6f028ca0e8edb4a8c9757ca4fdccab25fa1e0317da118810
 class Kernel extends Base {
 
   getApp(appName) {
+    if (appName === 'Acl') {
+      return this.functions.acl();
+    }
     return this.functions.getApp(KERNEL_APP_ADDR_NAMESPACE, this.appNamehash(appName));
   }