Revert Font Awesome 5 upgrade (#8810)

* Revert "Fix some icon names changed by the Font Awesome 5. (#8796)"

This reverts commit 3f9ec3de82.

* Revert "Migrate to font-awesome 5.0. (#8799)"

This reverts commit 8bae14591b.

* Revert "Fix some icons names, unavailable in fontawesome5 (free license). (#8792)"

This reverts commit b9c727a945.

* Revert "Update the icon name changed by the Font Awesome 5. (#8776)"

This reverts commit 17af4d27da.

* Revert "Add bot icon to bot avatars and migrate to newer version of Font Awesome (#8484)"

This reverts commit 4b794e134d.

app/javascript/mastodon/components/avatar.js

@@ -1,7 +1,6 @@
 import React from 'react';
 import PropTypes from 'prop-types';
 import ImmutablePropTypes from 'react-immutable-proptypes';
-import BotIcon from './bot_icon';
 import { autoPlayGif } from '../initial_state';
 
 export default class Avatar extends React.PureComponent {
@@ -66,9 +65,7 @@ export default class Avatar extends React.PureComponent {
         onMouseEnter={this.handleMouseEnter}
         onMouseLeave={this.handleMouseLeave}
         style={style}
-      >
-        <BotIcon account={account} />
-      </div>
+      />
     );
   }