unset RUBYOPT set by bundler

to not check for configured rubygems in external ruby scripts
called during packaging

added "with_env" wrapper
Merge remote-tracking branch 'upstream/master' into bundler_fix

Conflicts:
	lib/commands/ruby_command.rb
renamed with_env to save_env
Merge pull request #371 from lslezak/bundler_fix

Unset RUBYOPT set by bundler