make sure button text overflow is set to ellipsis

fixes #549

ui/styles/_buttons.scss

@@ -7,9 +7,11 @@
     @include transition(background-color .2s ease-in-out);
     @include transition(border-color .2s ease-in-out);
     @include transition(color .2s ease-in-out);
-
     outline: none;
     outline-color: white;
+    white-space: nowrap;
+    overflow: hidden;
+    text-overflow: ellipsis;
 
     &:hover {
         color: darken($gray, 10%);