Bunch of syc_import.py fixes.

This doesn't include all of @rtucker's changes.  I tried pulling them in
one-by-one, but the reworking of the multiprocessing stuff seemed to be
messed up on my end -- it was often dropping pages, etc.

This version of the import was tested on 2013-6-21 on Davis and resulted
in a full import with all pages, files, and maps (as far as I can tell).

There's still some polish needed, but this is good enough for a preview
site.