Add tycho-versions-plugin so we can manage versions

Allows us to do:
1) Update all poms/manifests with a ne versin number:
 mvn tycho-versions:set-version -DnewVersion=3.0.0
2) Sync pom version numbers to manifest ones
 mvn tycho-versions:update-pom
Add Tycho versioning help plugins
Set version number to 3.0.0-SNAPSHOT

using this command:
  mvn -o tycho-versions:set-version -DnewVersion=3.0.0-SNAPSHOT
Revert qualifer management
Mark all manifests with Eclipse-BundleShape: dir

Needed because unpack attribute in the feature.xml is ignored by Tycho
Set sourceEncoding to UTF-8 for plain text files

See http://maven.apache.org/general.html#encoding-warning
Remove settings that don't do anything
Upload P2 site to S3

We upload two URLs:
1) a per build/job URL that is persisted
2) a per branch which is replaced with each new job