d/source: Add debian-source-format
d/source: Add debian-source-format

Explicitly selecting a source format by putting the format in
debian/source/format is recommended. This allows for future removal of
the 1.0 default for the package source format and, depending on the
source format, may allow unambiguous declaration of whether this package
is native or non-native.

tcpcloud/contrail-packages,Juniper/contrail-packages,vpramo/contrail-packages,Juniper/contrail-packages,fpytloun/contrail-packages