Bump mocha and rake dependencies
It's only a test dependency
Minitest is not shipped by default anymore
Remove `debugging` flag. Leave `byebug` always on
Remove unnecessary stuff (byebug is always enabled)
Now `pry` starts at first line after `binding.pry`

Previously user would need to hit `next` one time to match `byebug`'s
behaviour. Now it's automatic.
Fix some issues when resetting the pry instance
Fix some whitespace issues
Improve comment
Complete gem description
Minor improvements in the tests
Bump byebug dependency
Don't finish pry instance when 'continue'

This should improve `pry-remote` support (see #13)