Update active support dependency
Rearrange gem groups to label some gems as offline

Meaning that they are not needed at runtime during regular use
or testing.
Add a rubocop configuration to the project
Put CONTRIBUTING.markdown in the gem

So that documentation generates correctly for tools like Dash.app
Oops
Remove active_support_selections in favour of all active_support core_exts
Port testing app to Swift

Since MacRuby is dead and GC is gone.
First pass at ripping out MacRuby support
First pass at updating and improving the test suite

Mostly just making things compatible with minitest 5.x
Update the History file
Fix some style issues that Rubocop complained about
Update version information
Merge remote-tracking branch 'ax/master'

* ax/master:
  Add a Bitdeli badge to README