Workaround for maven misresolving ${pom.version}

see http://jira.codehaus.org/browse/MNG-2796

The geronimo build has been having problems due to maven resolving ${pom.version} in dependencies which should be 3.0-incubating-SNAPSHOT to the timestamped version of the current pom rather than trying to resolve it for the dependency itself.

The workaround seems to be to define a ${version} property ourselves. jdillon did this quite a while ago in the geronimo build to workaround lots of similar issues.