Updated http requests to return both results or errors.

http request were originally designed to return only a result OR
an error, however this does not work in the case of on_error
being set to continue.  Updated to allow scenarios where both occur
as well as scenarios where multiple errors are returned.

Change-Id: Ibd4aecfe288b40f8661ba393207715a63c4d87db
Reviewed-on: http://review.couchbase.org/28973
Tested-by: Brett Lawson <brett19@gmail.com>
Reviewed-by: Matt Ingenthron <matt@couchbase.com>