Provide an action to clean rn-secure-storage in development mode

[itofarina]

Description
When the app is launched for the first time, it connects to the server and creates a user account. The server returns a key to the phone which is stored on the device using rn-secure-storage.
If the server is changed in the .env file, then the app will attempt to connect to the new server but no user exists there. Therefore, there needs to be a way to reset the app, including erasing the content stored in rn-secure-storage.
The current workaround is for the developer to completely uninstall the application, and reinstall it.

Proposed solution
The suggested fix would be if the app is running in development mode, had a button somewhere (perhaps the "me" page) to reset the app. This would erase all the content, and show a window that can not be closed. The developer can then completely close the app and relaunch it.

Description written by @jessgusclark (thanks!)