Make gremlin-groovy provided scope in hadoop-gremlin

Groovy is only used as part of the HadoopRemoteAcceptor utilized in the Gremlin Console (which uses the sugar plugin directly. as such, gremlin-groovy should already be present. no need to force this dependency to be available otherwise since the environment where this will be used will already be there.

In a sense this is a breaking change as someone depending on hadoop-gremlin who expects to get gremlin-groovy out of it, no longer will.