Changes button_to to link_to in collections_helper.

We changed the button_to to a link_to on the
actions_for_member method.  We were experiencing
problems with the confirmation and turbo links
when using the button_to.

Reworks test for Devise updates from 3.2.4 to 3.4
Adds password_length method to devise_user_shim model
Merge pull request #551 from projecthydra-labs/feature/link_to_collections

Changes button_to to link_to in collections_helper.