View source for Proposals/Objectionable content reporting

Currently Mahara supports objectionable material reporting for views only. The prossibility of reporting should not be limited to the views only and be extended to other Mahara features that potentially can contain objectionable material.

This is filed at https://bugs.launchpad.net/mahara/+bug/767569

====View====

It should be possible to report comments, notifications should go to Institution admin.

====Forum====

It should be possible to report posts, notifications should go to Forum Moderators.

* https://bugs.launchpad.net/mahara/+bug/1024872

====Wall====

It should be possible to report wall posts, notifications should go to the Wall owner.

====Blog====

It should be possible to report blog comments, notifications should go to the blog owner.

====Messaging====

It should be possible to report objectionable content in private messaging, notifications should go to the Institution admin.

====Automatic content filtering====

Objectionable content is currently only reported manually and thus may
never be discovered.

It might be possible to include a dictionary against which site content
is checked and put into the objectionable category for institution
admins (for profiles / pages that were created by a member of that
institution) / site admins (for groups and the default institution). It
will not be possible to find all offenses, e.g. if punctuation is found,
but some initial serious offender could be detected.

If this feature is implemented then:
* it should be disabled by default
* only flag content to be reviewed by the admin (i.e. the content is not taken down and is still accessible)

====in multi-tenannted Mahara====

Objectionable content notifications should only go to the institution admins who have the care over the person whose page / artefact etc. was reported. It is debatable if the site admins should receive the notifications as well if they don't receive the others above.

If the site admins do not receive all objectionable content notifications, they should have the possibility to see them somewhere in the admin area on a page to see an overview of what has been reported, how often things were reported etc. because institution admins or users may not do anything about the objectionable content.