Two action items: login/logout and settings.
Added android:logo, using the same as android:icon

For the moment, I don't see any problem on using the icon file we
have as the app's logo, although it's already used

Android Action Bar UI guide says that the logo should be wider and not
contain any text, while icon could. Since our icon is wide enough (from
my point of view) and does not contain any text, I think it's
appropriate to use it as a logo too.
ConfigurationWizard uses action instead of button.

New provider button has been converted to an action item, shown at the
bottom of the screen.
Dashboard action bar to the bottom of the screen.

If in Configuration Wizard we locate the action bar at the bottom of the
screen, we should remain consistent and do the same in Dashboard.
Authenticated status remembered after exit.

If the user presses the back button and returns to leap_android, the app
will show login or logout button remembering if s/he was authenticated
or not.

This fixes bug #3467.