Add suse support for the snaps build

Add suse support for the snaps build

suse snaps rpm build and test happens inside a docker container
This patch requires the following patch to be merged:

https://git.opendaylight.org/gerrit/#/c/68114/

It reuses most of the building and testing scripts and it avoids
duplicating the packaging-build-rpm-snap job using the variable
{distro} to differentiate between suse and epel.

Change-Id: I31ee0558f3cc76e27f462f1d3ac528b5906a122c
Signed-off-by: Manuel Buil <mbuil@suse.com>