Merge pull request #192 from alicial/update-stripe-dues

Update stripe dues
Fix busted Stripe spec, head hung low
Add separate login page

- Will become root_path once the external pages are deployed in their own separate app
Don't try to create a new auth if the current user already has it for that provider

- Fixes #146
- The sessions controller is kind of a nightmare, sad trombone
- Gratuitous single to double quotes replacement
Remove all the external DU pages

- Set a bunch of constants as links to external app
- Remove "Apply" dropdown from nav since we create an application when you auth
Update to modern shoulda-matchers 'validate_inclusion_of' syntax