For #1984: return 503 code

- also remove unnecessary tests on oxf:xforms-server output
- minor known issue: application/xml content-type header is still sent to client, but there is no body
For #2009: fix incorrect resources after db2779a80d1fb08f7ad9b579008f3bfef419ac43
For #635 and #1791: keep data in compatible format

- fixing b059ea5387976b2ba24a06653c14923a6ae0f11e (Bookshelf)
- fixing 1e37f77b00780be260afef9de82439706e12431d (DMV-14)
- data in compatible format
- form metadata has migration info
Minor: remove commented-out lines, spacing