Updated binding loading sequence.

Updated binding loading to give reasonable errors when
there is a library available, but there was an error allowing
it to load.  This can happen if the library was built for the
wrong arch or platform.

Change-Id: I7ce682b264a80d0226219465f3787f619541d74f
Reviewed-on: http://review.couchbase.org/30185
Reviewed-by: Mark Nunberg <mnunberg@haskalah.org>
Tested-by: Brett Lawson <brett19@gmail.com>