Migrate poiapp and libnaviapi-agl to AGL Gerrit

Update the poiapp and libnaviapi-agl recipes to point at AGL Gerrit for
their source repositories.  Additionally, the libnaviapi-agl recipe has
been moved to recipes-demo/navigation since being beside its users seems
to be a more logical location, and a few lines have been reordered in
the poiapp recipe to better match the OpenEmbedded style guide.

Bug-AGL: SPEC-2787

Change-Id: I41334b47b4970adb51fc943368dba7e07bbf113d
Signed-off-by: Scott Murray <scott.murray@konsulko.com>