Fix button with icons

[offtherailz]

• By default the theme uses float: left on glyphicons.
  http://lf.mapstore2.geo-solutions.it/samples/base/custom.html

This causes the issues with buttons and icons.

I suggest to include what is missing in css.css from custom.css and set float:left by default.

• The btn-group are by default 50px wide, only vertical btn-bars should have this limit.