Test against various Ruby implementations
Add Rubinius standard library gems
Use Ruby 1.8-compatible hash syntax
Replace stabby lambda with lambda keyword
Replace ::BasicObject with Naught::BasicObject
Conditionally define respond_to?/respond_to_missing?

I tried doing the same thing with alias_method/undef_method but it
caused errors on JRuby.
Ruby 1.8, Rubinius, and JRuby do not print the indication of blocks
Fix specs on Rubinius
Fix specs on JRuby