Expanded test_login.py

    - Expanded cfme/tests/test_login.py to include test_verify_password_update and test_verify_bad_password_update.

    - Also expanded login.py with more convenience functions (fill_login_fields, show_password_update_form, close_password_update_form, update_password, clear_fields)

    - Fixed (a possible typo in) area.locators['message'] locator for 5.3 in cfme/web_ui/flash.py. The previous locator did not work for me, and did not seem correct when I manually found the element in the webpage
It should be noted that the same form can be used. ``fill()`` doesn't blow up if you don't pass it a value that there is a form element for. Equally, if you pass it a form element value and there is no form element, it won't blow up either.