Start linting envs files, add task to only pylint errors, and move pylintrc file to the correct location

The MKTG_URLS dictionary is overwritten completely in aws.py anyway, and we
shouldn't be trying to keep both the production config and LMS code in sync
with changes to the marketing site.

* Fix indentation/line break issues
* Handle marketing root URL as a separate case in marketing_link
* Move link map to its own setting.

This functionality requires the Zendesk URL, user, and API key to be specified
in django.conf.settings. Also, add a flag to MITX_FEATURES (enabled by default)
to control the endpoint and the front-end feature (yet to be added).

This allows us to a) compile the coffeescript and sass from xmodules
using the new out-of-band method and b) reload xmodule static content
whenever it changes, which should make devs much happier.

When a user logs in this will drop a new cookie 'edxloggedin' that will
match the value and expire date of the django session cookie.
When a user logs out the cookie will be removed

  - ops view for the desktop app to talk to
  - xmodule that talks to the foldit model and displays the student's state
  - grading tweak to make grade updates from an external service work:
    - Add an always_recalculate_grades property to XModuleDescriptor.