fix logout icon
<md-list-item class="navi-link">
<a href="#" class="md-list-item-container md-button" v-on:click="logout()">
- <md-icon><i class="fa fa-sign-out fa-fw"></i></md-icon>
+ <md-icon><i class="fas fa-sign-out-alt fa-fw"></i></md-icon>
<span>Logout</span>
</a>
</md-list-item>
