split bundler-commands into seperate lines

This makes adding, deleting and merging a lot easier.
add sidekiq to bundler-commands

closes #2779
remove foreman from bundler-commands

closes #1825
remove spin from bundler-commands

closes #1817
remove ruby from bundler-commands

related to #1587
closes #2200
closes #2561
remove berkshelf from bundler-commands

fixes #2076
Add 'outdated' and 'platform' completions to bundler plugin
remove double bundle exec
add spring to bundler-commands
add pry to bundler-commands
added Bundler readme file
add BUNDLED_COMMANDS functionality to bundler plugin
Merge pull request #2923 from Kriechi/bundler-fixes

Bundler fixes