Update Ember to 3.1

app/utils/cps/bignumber.js

@@ -1,4 +1,4 @@
-import computed from 'ember-computed';
+import { computed } from '@ember/object';
 import ethers from 'npm:ethers';
 
 export default function(dependentKey, converterMethod) {

app/utils/cps/is-present.js

@@ -1,8 +0,0 @@
-import computed from 'ember-computed';
-import { isPresent } from 'ember-utils';
-
-export default function(key) {
-  return computed(key, function() {
-    return isPresent(this.get(key));
-  });
-}