Fix itests

So somewhere along the way, the chef_db integration tests stopped working -- it's odd because I thought they were running when I was working on the bulk_get adjustment. In any case, these patches get the itest stuff working again and pay down a good portion of the debt that had accumulated there.

The itests are now broken out into separate files. In the process, some tests were found that were not being run (and were broken) both fixed now.

I have a branch on top of these changes that switches the integration tests over to common test taking a similar approach to db setup as is done in och_chef_authz.

ping @sdelano @manderson26 @marcparadise @oferrigni @hosh