Add ability to manage all widget/applications

For system uses -like automatic testing-, it is
needed to include tha ability to list ALL installed
widgets and ALL running instance of installed
widgets.

This change adds the option -a or --all to the
commands 'list' and 'runners' for the purpose
of listing any installed widgets, even those
requiring to be hidden.

Example: afm-util ps -a

Bug-AGL: SPEC-2272
Bug-AGL: SPEC-1850

Change-Id: I216ec9c63efea1b3af58e1d2d7723d986e04551e
Signed-off-by: Jose Bollo <jose.bollo@iot.bzh>