pom.xml: updates for release 0.38
pom.xml: updates for release 0.38

Update killbill-commons to 0.6

Signed-off-by: Kill Bill core team <1a73af9e7ae00182733b2292511b814be66f065f@killbill.io>

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