(css) Improve sgImageGallery for small devices

Also include md-truncate directive from ng-material.

UI/WebServerResources/scss/styles.scss

@@ -60,6 +60,7 @@
 @import 'components/toast/toast';
 @import 'components/toolbar/toolbar';
 @import 'components/tooltip/tooltip';
+@import 'components/truncate/truncate';
 @import 'components/virtualRepeat/virtual-repeat';
 @import 'components/whiteframe/whiteframe';