update couchforms and receiver to test request abstraction

(the API has not yet been changed)
update couchforms and receiver to test

still no code changes on the calling end
use new API for SubmissionPost
Merge branch 'master' into extract-receiver-request
update receiver ref
Merge branch 'master' into extract-receiver-request
update couchforms and receiver refs
Merge pull request #2118 from dimagi/extract-receiver-request

Pass in receiver params explicitly