Add UH test CAS login

[philipmjohnson]

Please do work for this task in a branch called issue-12.

• Hook up CAS authentication following example in meteor-example-uh-cas
• Profile and filter pages require authentication.
• Landing and directory pages do not require authentication.
• When users login, the system checks to see if a Profile document exists for that user, and if not, one is created.

[philipmjohnson]

Finished. The landing page has a functional login button:

This takes you to the UH CAS test server. Once you are authenticated, the system creates a Profile document for you based on your username and takes you to the profile page provide further details:

Note that the navbar now has a logout button.

Finally, if you try to go to a page you are not authorized to go to, such as another user's profile or
filter page, you are not allowed: