[#315] Change settings.DOMAIN_NAME to settings.RSR_DOMAIN

Change all uses of DOMAIN_NAME to RSR_DOMAIN
[#315] change settings.APP_DOMAIN_NAME to settings.AKVOAPP_DOMAIN

Change all uses of APP_DOMAIN_NAME to AKVOAPP_DOMAIN and use getattr()
where appropriate.
[#315] Change request.app_url to request.akvoapp_root_url

Change all uses of app_url to akvoapp_root_url in  views, templates and
template tags.
Move settings.DEFAULT_FROM_EMAIL from 90-finish.conf to 20-default.conf

Also fix the use of the setting in a couple of places
Change a number of references to www.akvo.org to akvo.org or
rsr.akvo.org as appropriate
[#315] Fix partner site widgets' links when running on CNAME

When a PS widget is shown using the CNAME domain for the PS the links
point to to the akvoapp.org domain.

Fix by using request.META.HTTP_HOST instead of request.akvoapp_root_url
(refactored from request.app_url) where needed or by just using the path
when constructing hrefs.
Update media assets
[#315] Merge branch 'develop' of github.com:akvo/akvo-rsr into feature/cname_urls

Conflicts:
	akvo/rsr/templatetags/map.py
	akvo/scripts/asset_manager/map.py
Merge pull request #355 from akvo/feature/cname_urls

Feature/cname urls - reviewed and merged