Remove ruby2ruby dependency
Remove ruby2ruby dependency

This was just a Reek dependency which unfortunately allowed versions
`>= 2.0.8` instead of `>=  2.1.1`.

Now that Reek has moved on to use `parser` instead of `ruby_parser`, we
can safely remove this dependency (which was used to generate Ruby code
from `ruby_parser`'s s-expressions).

whitesmith/rubycritic,bglusman/rubycritic,whitesmith/rubycritic,fimmtiu/rubycritic,ancorgs/rubycritic,bglusman/rubycritic,fimmtiu/rubycritic,whitesmith/rubycritic,ancorgs/rubycritic,bglusman/rubycritic,fimmtiu/rubycritic,ancorgs/rubycritic,whitesmith/rubycritic