configure individual bintray
drop release plugin in favor of versions plugin
configure organizational bintray
change to valid groupId

This is a breaking change, but necessary for deployment to global repositories such as jCenter, Maven Central, etc. It corrects a temporary, but unsustainable, decision made back in 8e0ead74b953d3703f1cd72edf9be73225b7b9e9.

See also http://maven.apache.org/guides/mini/guide-naming-conventions.html
release v5.1-beta3

incantation:
$ mvn versions:set -DnewVersion=5.1-beta3