Revert "Only show case type select if creating new cases"

This reverts commit 0bc0b1e0fdcff1049641c260c03a69ab95ecf9da.
Refactorings that were in reverted commit
Require case type match to update
Fix busted external id updating
Make external id lookup only match specified type
Merge pull request #632 from dimagi/importer-type

Make case type meaningful on import