scheduler-groups and boost fix

Closes #2042 (closed) AND 1037

Test Plan for scheduling groups:

1. go to a group
2. schedule a post
3. refresh
4. The "scheduled: x" button should show a number of scheduled posts
5. Clicking on the scheduled button should show only the scheduled posts

Test Plan to check boost button not showing in scheduled posts:

1. schedule an activity (normal or in a group) or a blog
2. go to the scheduled post (in case of media, click to open for stand alone)
3. boost button should not be shown