Adds configuraiton for bundle --without <groups>

 - Optionally specify groups to bundle without instead of the default %w(test development)
Do not check app_user in jetty startup
Cannot use OpenStruct#java with jruby

 - It will return Java::Java rather than the specified property
 - Use java_binary instead
Use gem in path to install bundler

 - -S gem is using the gem shim from rbenv and choking becuase it is bash not ruby
Do not cleanse environment of BUNDLE_GEMFILE

 - Allows passing ENV['BUNDLE_GEMFILE'] to bundler to specify an alternate
   Gemfile