Click correct submit button

The CAPAcheck and TextInput tests broke with the Help Modal rollout.

The XPath selectors were ambiguous and clicked the submit button within
the (hidden) modal, instead of the problem's submit button.
Merge pull request #4 from stvstnfrd/stv/fix

Click correct submit button
added test for shib auth (just look for login screen)
add the new shib case to the suite