Add a :translate command to Gremlin Console

As a convenience it would be nice to be able to do:

gremlin> :translate python g.V().where(outE().count().is(2))
==>g.V().where(outE().count().is_(2)) 

This kind of command would make it easier for someone to take a Groovy example (which is the primary way Gremlin examples are written) and convert them to a language of a user's choice.