allow dcae consumer group configuration

allow dcae consumer group configuration

this allows to change the dcase onset processing
group behavior across pdp-ds.

if installation sets DCAE_CONSUMER_GROUP, all
PDP-Ds will share the same consumer group, therefore
will have exclussive processing of onsets.  Otherwise
if installation unsets it (blank), all pdp-d's will
process all onsets being placed in dcae topic on
dmaap bus

Change-Id: I4cc63005402ce66c09617b52dfad9a6094cbcb46
Issue-ID: POLICY-766
Signed-off-by: Jorge Hernandez <jh1730@att.com>