Fix kredits balance handling

Kredits are stored on the Token contract as uint256 / bignumbers with 18
decimal points. Just like Ether and required by the ERC20 standard.
So we need to work with bignumbers and format a bignumber value here.

app/models/contributor.js

@@ -1,12 +1,13 @@
 import { computed } from '@ember/object';
 import EmberObject from '@ember/object';
 import bignumber from 'kredits-web/utils/cps/bignumber';
+import kreditsValue from 'kredits-web/utils/cps/kredits';
 
 export default EmberObject.extend({
   // Contract
   id: bignumber('idRaw', 'toString'),
   account: null,
-  balance: bignumber('balanceRaw', 'toNumber'),
+  balance: kreditsValue('balanceRaw'),
   isCore: false,
   ipfsHash: null,
 

app/services/kredits.js

@@ -7,6 +7,8 @@ import { computed } from '@ember/object';
 import { alias, notEmpty } from '@ember/object/computed';
 import { isEmpty } from '@ember/utils';
 
+import formatKredits from 'kredits-web/utils/format-kredits';
+
 import config from 'kredits-web/config/environment';
 import Contributor from 'kredits-web/models/contributor'
 import Proposal from 'kredits-web/models/proposal'
@@ -109,7 +111,9 @@ export default Service.extend({
   },
 
   totalSupply: computed(function() {
-    return this.kredits.Token.functions.totalSupply();
+    return this.kredits.Token.functions.totalSupply().then(total => {
+      return Promise.resolve(formatKredits(total));
+    })
   }),
 
   loadInitialData() {

app/utils/cps/kredits.js

@@ -0,0 +1,25 @@
+import { computed } from '@ember/object';
+import ethers from 'npm:ethers';
+//import formatKredits from 'kredits-web/utils/format-kredits.js';
+
+function formatKredits(value, options) {
+  let etherValue = ethers.utils.formatEther(value);
+  if (!options.decimals) {
+    etherValue = parseInt(etherValue).toString();
+  }
+  return etherValue;
+}
+
+export default function(dependentKey, options = {}) {
+  return computed(dependentKey, {
+    get () {
+      const value = this.get(dependentKey);
+      return formatKredits(value, options);
+    },
+    set (key, value) {
+      const bnValue = ethers.utils.bigNumberify(value);
+      this.set(dependentKey, bnValue);
+      return formatKredits(bnValue, options);
+    }
+  });
+}

app/utils/format-kredits.js

@@ -0,0 +1,9 @@
+import ethers from 'npm:ethers';
+
+export default function(value, options = {}) {
+  let etherValue = ethers.utils.formatEther(value);
+  if (!options.decimals) {
+    etherValue = parseInt(etherValue).toString();
+  }
+  return etherValue;
+}