Modify publishing to send packages into bintray.

* Use rpm repository for rpms
* Use debian repository for debians
* Use generic repository for everything else.

Note: we still need to mark a release as public afterwards with an API call.  Need to figure that one out for automation.
Merge remote-tracking branch 'origin/wip/bintray-publishing' into full-bintray

Conflicts:
	project/build.properties
	project/packaging.scala
Fix publishing to bintray to automatically make artifacts available after succesful upload.
Merge pull request #61 from sbt/full-bintray

Full bintray publishing