Add notification source to notifications

[kkrysiak]

Many of the notifications are intuitive but I found myself confused by the generation of some subscription notifications. For example, I received notifications about someone submitting an evidence item and its subsequent actions (accepted, revised, etc). However, I was not at all involved in this evidence item. After digging around I realized I had generated the variant summary (not obvious by the life cycle events displayed due to subsequent changes) and commented on it which must have triggered my subscription to it.

Perhaps a "subscribed to: _____" on the right side of the notification bar? It could be specific "Subscribed to MET / EXON 14 SKIPPING MUTATION" or more general "Subscribed to: Variant" since the specific gene, variant, EID are included in the notification.