Add vendor/cache directory

[map7]

For my project I keep a vendor/cache directory just incase rubygems goes down and bummr doesn't play nicely with this directory as it doesn't add it to git when committing. I propose that the following line be changed to include the vendor/cache directory when committing changes.

https://github.com/lpender/bummr/blob/7f10a29797111d6a0464d3f520dace4e06d20b23/lib/bummr/updater.rb#L39

[map7]

I propose something like this; system("git add Gemfile Gemfile.lock vendor/cache")

[lpender]

This is fixed, thanks