Stash Notification Client

Per STASH-2839, even small development teams generate too much email traffic from Stash. While that ticket suggests digest-like functionality, I think that a free Stash notification client (for OS X, Windows, Linux, iOS and Android apps) would be a good idea.

It would be able to notify on every change to open PRs that the user is associated with and show a # of notification on the app icon. After clicking on the app icon, it would show a list of open PRs that the user is associated with (scrollable) with the most recently notified PRs on top and # of new notifications by each open PR as a number by the PR name.

See attached mockup. In addition, this would mean that Stash would need to keep track of whether a commit/comment had been viewed, which is mentioned in STASH-3781. (Unread comments/commits with new messages should possibly either be moved to top or stash browsing UI should allow a way to hide everything but commits with unviewed comments and should identify new comments. The interface should also be usable with these changes if developers have the PR open and are in the middle of making comments while others are commenting with minimal distractions; possibly a single number in the interface in the upper-right that increments as new things are happening in the background, and when click on that it shows a summary list of new events to PRs without redirecting from the current page where a comment might be in-progress.)

It doesn't have to be exactly like this to work, but just providing an idea for something that would help developers organize and deal with a lot of comments on commits on various PRs that may have happened in the hours that they were away while still allowing people to work with Stash in real time.