Add some optional policies around password resets, such as password reuse, forced password resets, allowed frequency of password resets

Conflicts:
	lms/envs/aws.py
	lms/envs/common.py
image-explorer: add reference to image-explorer
make GA account code configurable as well as allow GA to appear on courseware. Also, make the GA account ID configurable rather than hard coded in the Mako template

Conflicts:
	lms/envs/aws.py
	lms/envs/common.py
freetext-mrq: Add fork of the mentoring XBlock repository