Update getImportedExportedKeys() which tracks table constraints to
include correctly fetching/setting the deferrability column for the
foreign keys. Include more, previously disabled, tests for
functionality.
Remove dead code
Fix two test results in the new-enabled tests. Add a little cleanup to
ensure tests don't leave anything behind.
merge tjoneslo: Update getImportedExportedKeys() which tracks table constraints

Merge pull request #37 from FoundationDB/sql-layer-adapter-jdbc/set-deferrability
https://github.com/FoundationDB/sql-layer-adapter-jdbc/pull/37