SCT-1701 unread count

[briehl]

Add counts of unseen notifications for each feed queried.

This changes the result structure of GET /notifications (and GET /notifications/global) from

{
    global: [note array],
    user: [note array]
}

to

{
    global: {
        feed: [note array],
        unseen: int
    },
    user: {
        feed: [note array],
        unseen: int
    }
}

[briehl]

Needs some frontend fixes before deployment

[coveralls]

Pull Request Test Coverage Report for Build 150

• 11 of 12 (91.67%) changed or added relevant lines in 2 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.07%) to 90.901%

---

Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
feeds/feeds/notification/notification_feed.py	6	7	85.71%

Totals
Change from base Build 149:	0.07%
Covered Lines:	969
Relevant Lines:	1066

---

💛 - Coveralls