refactor(Icons): use icons from zanata-ui

zanata-editor/src/app/app.css

@@ -24,7 +24,6 @@
 @import './components/Dropdown/index.css';
 @import './containers/EditorHeader/index.css';
 @import './css/heading/index.css';
-@import './components/Icon/index.css';
 @import './css/links/index.css';
 @import './components/TextDiff/index.css';
 @import './components/LogoLoader/index.css';

zanata-editor/src/app/components/DocsDropdown.js

@@ -1,6 +1,6 @@
 import { encode } from '../utils/doc-id'
 import Dropdown from './Dropdown'
-import Icon from './Icon'
+import { Icon } from 'zanata-ui'
 import React, { PropTypes } from 'react'
 
 /**

zanata-editor/src/app/components/FilterToggle/index.js

@@ -1,5 +1,5 @@
 import cx from 'classnames'
-import Icon from '../Icon'
+import { Icon } from 'zanata-ui'
 import React, { PropTypes } from 'react'
 
 /**