Add odl-faas-base feature into distribution.

Add odl-faas-base feature into distribution.

Recently, a merge in groupbasedpolicy [0]
has happened around the same time as distribution failures appeared,
which looked similar to the ones which lead to removing Faas.

But a fix in Vpnservice showed those failures are no more [1],
so perhaps now also Faas features will pass SingleFeatureTest.

However, Faas project has commented out odl-faas-all feature,
si this Change only adds odl-faas-base feature.

[0] https://git.opendaylight.org/gerrit/29419
[1] https://git.opendaylight.org/gerrit/32331

Change-Id: Ibd99a944c78ecc3bad0e0c36aa0602123594d42c
Signed-off-by: Vratko Polak <vrpolak@cisco.com>