Add more postgres support (#2080)

* reload the right data

More passing postgres tests

Handle schema updates, and $in for non array columns

remove authdata from user and implement ensureUniqueness

Make some tests work, detect existing classes

Throw proper error for unique index violation

* fix findOneAndUpdate

src/RestWrite.js

@@ -89,7 +89,7 @@ RestWrite.prototype.execute = function() {
     return this.cleanUserAuthData();
   }).then(() => {
     return this.response;
-  });
+  })
 };
 
 // Uses the Auth object to get the list of roles, adds the user id