Trigger custom comment events on comment add/remove/reply
Use commented object as context instead of comment within event trigger

- In order this to work with plone.contentrules use commented object as
  the main context within custom discussion events and add comment as the
  second parameter.
Update change log
Add custom content rules string substitutions

- Add content rules string substitutions for comment:
  - id
  - text
  - author email
  - author user name
  - author full name
Remove hard dependency on plone.stringinterp
i18n update
Merge pull request #47 from eea/2.2.x

Trigger custom events on comment add/remove/reply (git chery-pick from master branch)