Additional unit tests

I've written unit tests for g.v(), dedup(), groupCount(), copySplit()/_()/fairMerge() so far, and I'll probably write a few more as I test all the functionality I'm using in gremlin-node 0.1.14. Commit 56d167c is particularly important, since without copySplit dies without it. I have also included a commit fixing g.v() in this branch, which we can rebase out if you decide you want to push the consolefix branch prior to this one (or I can remove the fix from consolefix if you decide you want to push this one first).