models.py:
- BUGFIX: prevent duplicate projects returned from get_projects_user_can_view

views.py:
- edit_project: don't use @permission_required decorator, check against project instance via has_modify_permission method
view_project_compensations.html:
- fix over-indentation
- check permissions for add comp matrix link

views.py:
- add_site, edit_site:
   - don't use @permission_required decorator, check against project instance via has_add_permission method
- view_compensations: determine comps to return based on project and site permissions
- add_compensation:
   - add request arg to CompensationForm to allow form to check user perms
- add_site_compensation:
   - add request arg to CompensationForm to allow form to check user perms
   - don't use @permission_required decorator, check against site instance via has_add_permission method