JOINDIN-398 Add event attendance functionality
Fix usage of the event api
Move the event attending string to the template
Added an about page as per the ticket requirements
Added a link to the new page in the navigation list
Fix typos in about copy and add an additional sentence.
Add a little more spacing after a paragraph and before an h2.
Merge branch 'pr89'
t pus
Fix mailto: link on about page.
Merge pull request #90 from akrabat/email-link-fix

Fix mailto: link on about page.
Merge branch 'JOINDIN-398' of github.com:martynthewolf/joindin-web2 into pr86
Improve look of 'I'm attending' button
Redirect back to event detail page if that's where we started
Merge branch 'pr86'
Merge remote-tracking branch 'upstream/master'
Merge branch 'JOINDIN-Fix_add_comment_usage_of_api_model' of github.com:martynthewolf/joindin-web2 into pr87
Merge branch 'pr87'
Merge branch 'master' of github.com:joindin/joindin-web2 into fix-attendee-string

Conflicts:
	app/templates/Event/_common/event_header.html.twig
	app/templates/_common/eventsummary.html.twig
Code cleanup: there should be no functional changes here
CSS tweak to the attending button to make it a bit smaller