Add PUT endpoint for editing an activity's comment
Add POST endpoint for creating activities on a WP
Remove error responses

It is planned to describe the possible error responses at a unique spot.
So, we remove it from the single endpoints.
Merge branch 'master' into feature/13954_add_edit_quote_comments_in_wp_overview

Signed-off-by: Alex Coles <alex@alexbcoles.com>

Conflicts:
	apiary.apib
Merge pull request #3 from opf/feature/13954_add_edit_quote_comments_in_wp_overview

[Feature] 13954 add edit quote comments in wp overview