Remove Ning HTTP client
[maven-release-plugin] prepare release 1.6
[maven-release-plugin] prepare for next development iteration
move to airbase
use release versions
[maven-release-plugin] prepare release 1.7
[maven-release-plugin] prepare for next development iteration
Upgrade to airbase 4.
[maven-release-plugin] prepare release 1.8
[maven-release-plugin] prepare for next development iteration
minor updates

- update to 0.74-SNAPSHOT (which renames some artifacts).
- rename the base pom to discovery-root.