Track down memory leaks in Go frontend

[qpfiffer]

CUnjar looks pretty clean, but you can watch memory usage slowly creep up if you just keep unjarring the same key over and over again. My go expertise isn't good enough to know where it's happening. I'm also pretty sure that it's not in the storage engine, because valgrind on ./run_tests.sh is clean.

[kyleterry]

tired now but will later

[qpfiffer]

@kyleterry I dunno where they're happening, would be cool to pair on it. I'm pretty sure all the C -> Golang stuff is clean, but I guess not.