Add lobby icon from "room service" Material Design icon

Copied from "places/svg/production/ic_room_service_24px.svg" of
"https://github.com/google/material-design-icons", tag 3.0.1.

Material Desig icons 3.0.1 are licensed under the Apache 2 License.

Signed-off-by: Daniel Calviño Sánchez <danxuliu@gmail.com>

css/style.scss

@@ -605,6 +605,7 @@ input[type="password"] {
 @include icon-black-white('menu-people', 'spreed', 1);
 @include icon-black-white('no-password', 'spreed', 1);
 @include icon-black-white('share-window', 'spreed', 1);
+@include icon-black-white('lobby', 'spreed', 1);
 
 #app-sidebar .close {
 	position: absolute;

img/lobby.svg

@@ -0,0 +1 @@
+<svg xmlns="http://www.w3.org/2000/svg" width="24" height="24" viewBox="0 0 24 24"><path d="M2 17h20v2H2zm11.84-9.21c.1-.24.16-.51.16-.79 0-1.1-.9-2-2-2s-2 .9-2 2c0 .28.06.55.16.79C6.25 8.6 3.27 11.93 3 16h18c-.27-4.07-3.25-7.4-7.16-8.21z"/></svg>