Don't include Gemfile* in composer zipballs
Don't include Gemfile* in composer zipballs

composer (via GitHub) excludes files listed in .gitattributes. Gemfile* are
build files and don't need to be included.

Change-Id: I612b3af26c25465654844584ffdb15265eb0262c

wikimedia/oojs-ui,wikimedia/oojs-ui,wikimedia/oojs-ui,wikimedia/oojs-ui