Make course ids and usage ids opaque to LMS and Studio [partial commit]

This commit updates lms/templates.

These keys are now objects with a limited interface, and the particular
internal representation is managed by the data storage layer (the
modulestore).

For the LMS, there should be no outward-facing changes to the system.
The keys are, for now, a change to internal representation only. For
Studio, the new serialized form of the keys is used in urls, to allow
for further migration in the future.

Co-Author: Andy Armstrong <andya@edx.org>
Co-Author: Christina Roberts <christina@edx.org>
Co-Author: David Baumgold <db@edx.org>
Co-Author: Diana Huang <dkh@edx.org>
Co-Author: Don Mitchell <dmitchell@edx.org>
Co-Author: Julia Hansbrough <julia@edx.org>
Co-Author: Nimisha Asthagiri <nasthagiri@edx.org>
Co-Author: Sarina Canelake <sarina@edx.org>

[LMS-2370]

lms/templates/conditional_module.html

@@ -4,7 +4,7 @@ from django.core.urlresolvers import reverse
 
 def _message(reqm, message):
     return message.format(link="<a href={url}>{url_name}</a>".format(
-        url = reverse('jump_to', kwargs=dict(course_id=reqm.course_id,
+        url = reverse('jump_to', kwargs=dict(course_id=reqm.course_id.to_deprecated_string(),
                         location=reqm.location.url())),
         url_name = reqm.display_name_with_default))
 %>