pom.xml: updates for release 0.39
pom.xml: updates for release 0.39

Update killbill-commons to 0.7

Signed-off-by: stephane brossier <c1fb28815da1df8a6921017a648d6c4b5d859b78@groupon.com>

killbill/killbill-oss-parent,andrenpaes/killbill-oss-parent,maguero/killbill-oss-parent,rocketlawyer/killbill-oss-parent