Added post report feature

You can report a single post by clicking the correct icon in the controler section

Workflow:
* Report a post as offensive
* Trigger alerts to every pod-admin
* Pod-admin can review it in the admin interface
* Delete the post or mark it as reviewed
Merge pull request #4517 from Zauberstuhl/report_post_feature

Added post reporter feature

Conflicts:
	Changelog.md
	app/assets/stylesheets/application.css.sass
	db/schema.rb