Now the user can only login locally if the user institution do not restrict login via federation.

refs #1242
Fixed bug in method #after_sign_in_path (application_controller).
The bug was causing a redirect loop.

refs #1242
For some institutions (with force_shib_login enabled) local login and registration are not available.

refs #1242
Authentication is now verified inside file overrides.rb (devise->authenticate)
and registration before_filter: check_shib_login_only  was updated.

#refs 1242
Merge branch 'branch-v2-1242-force-shib-login' of git://github.com/gmiotto/mconf-web into gmiotto-branch-v2-1242-force-shib-login

Conflicts:
	app/controllers/registrations_controller.rb
	app/models/institution.rb
	db/schema.rb
	lib/devise/overrides.rb
	spec/controllers/registrations_controller_spec.rb
Fix deprecation warnings on tests
Review of PR #6, most changes in the tests

refs #1242
Merge PR #6 from 'gmiotto/branch-v2-1242-force-shib-login' into branch-v2