Dataserver bugfixes

Move datastore default paths out of /tmp into /var
Add upstart config files for running HTTPDataStore
Move writeback check inside parseconfig so that config_help reflects /etc/server.local.yaml modifications
Fix auth_tests so they are actually registered
Add test for failure to strip padding that broke HTTPDataStore registration
Change grr_server to allow it to start master/slave dataservers
Let's just remove the Dataserver.path config option and use Datastore.location exclusively.