Remove Gemfile.lock from the gem

[vassilevsky]

"When developing a gem, use the gemspec method in your Gemfile
to avoid duplication. In general, a gem's Gemfile should contain
the Rubygems source and a single gemspec line.

Do not check your Gemfile.lock into version control,
since it enforces precision that does not exist in the gem command,
which is used to install gems in practice.

Even if the precision could be enforced, you wouldn’t want it,
since it would prevent people from using your library
with versions of its dependencies that are different
from the ones you used to develop the gem."

http://yehudakatz.com/2010/12/16/clarifying-the-roles-of-the-gemspec-and-gemfile/

[lucasmazza]

We have the lockfiles in the repo to share the result of bundle install across multiple travis builds to faster feedbacks when changing stuff. It's not a perfect solution at the moment (since we have to juggle with multiple lockfiles) but it's worth at the moment.

[josevalim]

I have explicitly disagreed with Yehuda about this (and he knows ;)). The Gemfile.lock should stay in the repository because contributors and developers should be able to fork the project and run it using versions that are guaranteed to work.

If someone wants remove the "precision" which Yehuda mention, the best is to remove the lock file in the CI server, although that poses its own problems as @lucasmazza mentioned.