Change logout to log out, because consistency

ui/src/auth/Purgatory.js

@@ -90,7 +90,7 @@ class Purgatory extends Component {
                 </div>
               : <p>You are a Lost Soul</p>}
             <a href={logoutLink} className="btn btn-sm btn-link auth--logout">
-              Logout
+              Log out
             </a>
           </div>
         </SplashPage>

ui/src/side_nav/components/UserNavBlock.js

@@ -94,7 +94,7 @@ class UserNavBlock extends Component {
             className="sidebar-menu--item sidebar-menu--item__logout"
             href={logoutLink}
           >
-            Logout
+            Log out
           </a>
           <div className="sidebar-menu--heading sidebar--no-hover">
             {me.name}