gitignore Gemfile.lock

The Gemfile.lock shouldn't be included in a gem-based repository
because it may artificially lock obsolete gems.

An example of this is rb-fsevent which at the version it was
locked at is incompatable with OS X 10.8

If something does need the version locked, specify it in the
.gemspec or Gemfile itself.
Merge pull request #28 from docwhat/gemfile_lock

gitignore Gemfile.lock