Change ODL repo to nexus.opendaylight.org

Change-Id: I242945edba84b891ccbf82d5fcce8ef5fe37ad3d
(cherry picked from commit 939a560)

Author: mnasiadka

docker/base/opendaylight.repo

@@ -1,6 +1,5 @@
 [opendaylight]
-name=CentOS CBS OpenDaylight Release Repository
-# opendaylight package is not signed, so download from HTTPS source at least
-baseurl=https://cbs.centos.org/repos/nfv7-opendaylight-6-release/x86_64/os/
+name=OpenDaylight Carbon
+baseurl=https://nexus.opendaylight.org/content/repositories/opendaylight-carbon-epel-7-x86_64-devel/
 enabled=1
 gpgcheck=0