refactor
If nil return value, use the form buffer instead

closes #887
Merge pull request #1996 from Daxter/bugfix/887-form-buffers

[887] Respect the form buffer!
rollback shoulda-matchers
Merge branch 'bugfix/rollback-mocha' of https://github.com/Daxter/active_admin into 1791-fix-signout-redirect-in-scoped-route