Allow site news to be displayed at course level

[Jeremy Hopkins]

I believe currently the block is hard coded to hide site announcements on course level instances.

If so this code should be removed and use the block instance settings which already allow:

• Site + Course
• Course Only
• Site Only

[Manoj Solanki]

Fix #26. Also fix issue with incorrect number of total posts appearing for course announcements.

→ <<cset 889dd1df70d5>>