Merge pull request #8 from bparees/master

switch return code so sti doesn't fail
Run 'bundle clean' after installing gems to get rid of unused gems
Added helper for shebang scripts using /usr/bin/ruby
Run gem install/update without installing rdoc/ri to speed up build
Add 'Gemfile.lock' into artifacts and make path relative to $HOME
Reorganize the repository layout to minimize the number of layers in Docker image
Merge pull request #11 from bparees/master

create src dir before copying into it
Merge pull request #10 from mfojtik/ruby_improv

Various ruby image improvements