(#429) Ensure btn-sm has no set height

This ensures the .btn-sm class is not effected with a minimum height
like normal buttons.

Author: st3phhays

scss/components/_buttons-badges.scss

@@ -1,4 +1,4 @@
-.btn {
+.btn:not(.btn-sm) {
     min-width: 45px;
     min-height: 45px;
 }