I#28233: Remove border-radius: 0 from input styling

The input style (not only for type=text as showed the requestor but the
dropdowns too) is buggy on Firefox with weird round corners and general
look&feel.

Applying the "patch" fixes the issue and doesn't affect other browsers.
Additionally, remove the "-moz" and "-webkit" rules since the modern
browser releases don’t require them anymore, as they have all adopted
the oficial CSS3 syntax.
Merge branch '4.2/rudder-input-styling-on-ff' into 4.2-trunk