Add Bundler byproducts to the list of ignored files.

I assume this commit is self-explanatory...
Remove redundant `include` call in system spec helper.

`rspec-system-puppet` helpers are already included few lines above the deleted
line, which by the way would have no effect anyway.
Merge pull request #252 from stefanozanella/update_gitignore

Add Bundler byproducts to the list of ignored files.
Merge pull request #253 from stefanozanella/spec_helper_fix

Remove redundant `include` call in system spec helper.
FM-103: Add metadata.json to all modules.
Merge pull request #255 from apenney/metadata

FM-103: Add metadata.json to all modules.