Fix Fragment BackStack and Titles

Related to bug #12939786 and bug #13223838

- first use Fragment BreadCrumb for managing Titles and Back
- consider the first fragment as the initial one (both in the
normal case and in the shortcut one)
- fix usage of the Fragment BackStack so that in all cases we
are returning to the initial Fragment before exiting the App.

Change-Id: I96989d14f4e88688747b93ab9fadd96aea214a2c