Fix GH issue #64 - underscores in foreign key actions

* When extracting composite foreign keys to explicit constraints,
  convert the ON UPDATE/DELETE action constant to SQL
* Fixed latent issue with update/delete actions switched in the
  constraint definition
* Added extraction test for the above issues
Re-set quoting rules during extraction test
Merge pull request #65 from austinhyde/composite-fkey-ref-actions

Fix GH issue #64 - underscores in foreign key actions