Develop: Add logout capability

[mdconatser]

As a user, I want to be able to log out of the application in case I need to switch email accounts or just sign out in general. This already exists within the application, but should be updated to function with the new login approach.

Acceptance Criteria

• Application contains a function to log out (via navigation or in settings)
• 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]

if you log out and close the app, then reopen the app, it automatically logs me in again. i was logged in with a normal username/password, not google

[mdconatser]

tested on android

[tatikozh]

tested on iPad