Develop: Clear all notifications

[cthorn2]

As a user, I want a quick way to be able to clear all my current notifications at the same time.

Acceptance Criteria

• Button to clear all notifications is added to the notifications view.
• Upon being tapped, button clears all notifications.
• Document any relevant content in the Programmer guide (draft thoughts of usage and importantly the "Why")
• Updates SRS and STP (and other docs if necessary)
• Add/Update relevant unit tests

[mdconatser]

tested on android, entered a bug to fix recurring notifications