[build] Prepare 0.2.x and switch to -SNAPSHOT scheme (#75)
This commit switches the effort on master from 0.1 to 0.2.0.
It also introduces a new versioning scheme, using -SNAPSHOT
instead of .BUILD-SNAPSHOT as the qualifier for snapshots.
The whole scheme is detailed in the reference documentation,
and adaptations are made to the build script to accommodate it.
[build] Polish: remove old entries in developers
List of developers in pom.xml should usually not contain devs that
should no longer be contacted about the project.
