This adds a field to the post headers and some more tests.

This also adds a confirmation dialog to the removal process.

* Set filterTouchesWhenObscured for all views
* Warn the user if Apps using the SYSTEM_ALERT_WINDOW permission are installed
* Warn the user if an App using the permission is installed while Briar is running

Signed-off-by: goapunk <noobie@goapunks.net>

Also fixed a bug with settings namespaces.

The toolbar subtitle shows information about how many contacts the
current blog is shared with and how many of those are online.

* Remove distinction between "shared with" and "shared by"
* Show all contacts a blog is shared with
* Show online status of contacts in sharing screen