Allow release:prepare to rewrite the versions

Allow release:prepare to rewrite the versions

- If an artifact has a version number defined in a different POM the
release process doesn't try to rewrite the variable in the other pom
file, that is because that may have a cascaded effect on otehr poms
file, so the possible fixes are:
	- avoid the global variables as version numbers
	- use dependencyManagement section to avoid duplications also
	for the project artifacts.
The last option is by far more elegant and functional and is
implemented in this patch.

Signed-off-by: Giovanni Meo <gmeo@cisco.com>