Whitespace fixes.
Add the default .rspec
Add standard RSpec configuration
Disable random sorting of specs

Makes runner specs go forever with certain seeds (e.g. --seed 6871),
disabled until the runner will run specs in a subshell. Ref:
https://github.com/elia/rspec.tmbundle/commit/92bd792d813f79ffec8484469aa9ce3c7872382b#commitcomment-7325726
Fix the switch command

- add a default describe with type subject
Fix an edge case in the switch command
Use #system instead of #`
Expand file contents to make them more readable
Extract the “described” builder and add specs

And thanks to @noniq for forcing me to write specs and fix a couple of bugs (it was only working with rails projects).
Use `FileUtils.mkdir_p` for creating directories.
Merge branch 'elia-switch-command-fix' into master

This is basically #88, but I reordered and squashed some commits.