Username above toot box UI changes (#2418)

* Makes username above toot box into a link.

* Prepends username above toot box with an @.

app/assets/javascripts/components/features/compose/components/navigation_bar.jsx

@@ -14,7 +14,9 @@ class NavigationBar extends React.PureComponent {
         <Permalink href={this.props.account.get('url')} to={`/accounts/${this.props.account.get('id')}`}><Avatar src={this.props.account.get('avatar')} animate size={40} /></Permalink>
 
         <div className='navigation-bar__profile'>
-          <strong className='navigation-bar__profile-account'>{this.props.account.get('acct')}</strong>
+          <Permalink href={this.props.account.get('url')} to={`/accounts/${this.props.account.get('id')}`}>
+            <strong className='navigation-bar__profile-account'>@{this.props.account.get('acct')}</strong>
+          </Permalink>
           <a href='/settings/profile' className='navigation-bar__profile-edit'><FormattedMessage id='navigation_bar.edit_profile' defaultMessage='Edit profile' /></a>
         </div>
       </div>