comment moderation: 2 emails are sent when publishing a comment

[Cecilia Vela Gurovic]

Bug description: Always take public anonymous comments through moderation

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Environment tested: Master
Browser tested: Chrome

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Manual Test Script
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Precondition:
UserA_01Page exists
 - open to public
 - share > advance options > Moderate comments = Yes
 - comments block on page
UserA_02Page
 - open to public
 - share > advance options > Moderate comments = Off
 - comments block on page

Test Steps:
1. UserB log in
2. comments on UserA_01Page
3. comments on UserA_02Page
4. UserB log out
5. comments on UserA_01Page http://mahara/view/view.php?id=10
6. comments on UserA_02Page http://mahara/view/view.php?id=9
7. UserA log in
8. Inbox displays
9. New comment on Page UserA_01
10. Request to change private comment to public
11. New comment on Page UserA_02
12. Request to change private comment to public
13. New comment on Page UserA_02

Expected Result: User recieves 1 email
  * Request to change private comment to public <subject: Bob NOT LOGGED IN has requested that you make their comment public.>
Actual Result: User recieves 3 emails
Request to change private comment to public <subject: Bob NOT LOGGED IN has requested that you make their comment public.>
  * New comment on Page UserA_01<subject: Bob NOT LOGGED IN (Link to page: Page UserA_01)>
Should only have 1 email sent to user = Request to change private comment to public