Navring: fix NPE if app uninstalled and in Navring

Change-Id: Iec7f79f9d7c236d2afe3788dc35f890b2e3c4f84
NavRingHelpers: Catch NameNotFoundException

If App is is uninstalled with a shortcut set for it, it will cause FC city.
Catch it and return blank target

PS2: Include import of exception..durr

Signed-off-by: bmc08gt <bmc08gt.teamb00sted@gmail.com>
Change-Id: Ie6379c3b45c22269852f7f28b4021f7bfff25f2b