A working draft/example/suggestion for a plugin architecture with named views and plugin context and iframe plugin pointing straight to the service url with the plugin context available in the url parameters.
Merge branch 'master' into ExternalIFramePlugIn

Conflicts:
	assets/css/main.css
	exercise/submission_models.py
	userprofile/models.py
Merge branch 'master' into ExternalIFramePlugIn
Some quick code to get EmbeddedTabs to work. This is mostly throw-away.
Tab apps to the menu.
added todo
Merge branch 'ExternalIFramePlugIn' into apps
todo entry
ExternalIFrameTab model and model admin, plugin renderer and template for it.
Merge branch 'EmbeddedTab' into ExternalIFrameTab

Conflicts:
	apps/admin.py
	apps/plugin_renderers.py

Also made view_tab to call get_renderer_class and added that method to EmbeddedTab too.
Added get_renderer_class for EmbeddedTab
Merge branch 'EmbeddedTab' into ExternalIFrameTab
CAUTION: Schemamigration! Simply adding new model. Forgot this from the commit where the model was actually implemented.
Merge branch 'ExternalIFramePlugIn' into apps
Removed borders from the iframe tabs
Added plugins to view_exercise and view_instance.
Merge branch 'master' into apps
Made the usage of the plugin renderers consistent in all the templates that had plugins.
Added sanitize filter to the plugin renderers in the templates.
Just doing some clean-up