Fix RVM hook for updating RubyGems
Fix RVM hook for updating RubyGems

The previous hook was faulty, resuling in alway attempting to
update RubyGems.

This commit fixes the quoting rule, so that the hook checks
RubyGems version correctly.

andyli/travis-build,andyli/travis-build,craigcitro/travis-build,craigcitro/travis-build