Fix UUID conversion in some places.

I'm pretty sure we're prematurely converting UUID objects to alphanumerics - we
have more than we actually need.
It's not too big a problem right now, since we're still calling convertUUIDs
wherever we need, and that one has a hack to check for _id columns and convert
already alphanumeric/binary strings back to UUID's.

We still shouldn't be doing the premature conversion in ObjectLocator, though,
and only do it where we need it.

Change-Id: I7f30d8a05e2861ee3a11d2359547d3142e0892c1
Merge "Fix UUID conversion in some places."