(#1253) - Ensure we only start the tests once
(#1257) - Escape _id in bulkDocs for WebSQL

Before this fix, quotes in doc ids inserted using
bulkDocs would crash WebSQL, since we were just
wrapping quotes around the id string.

I also went ahead and ensured that the WebSQL
adapter properly reports SQLError objects, since
before it would only give an unhelpful 500 with
no message.
(#1245) Use tmp directory for test dbs and remove it afterwards.

Instead of the temporary databases being created in the repository base they are created in './tmp'
(#1276) - bulkDocs with empty doc list is now valid