More transition to v2 IO

This replaces most mentions of the specific v0/v1 structures in the test
code to ones specified via the new lcb_start_loop/lcb_stop_loop API
calls.

Additionally, it fixes some bugs in iotable and iofactory which
prevented a v2 plugin from being loaded.

Change-Id: Ia77bf5eb2af918716a80de9802287100419524dd
Reviewed-on: http://review.couchbase.org/33597
Reviewed-by: Brett Lawson <brett19@gmail.com>
Tested-by: Mark Nunberg <mnunberg@haskalah.org>