REEF-43: Get version number from pom (via properties file)

This addresses https://issues.apache.org/jira/browse/REEF-43

The injectable class `Version` now gets the version number from pom (via a properties file).

Does the value look like "0.10-incubating-SNAPSHOT"? If yes, in REEFVersion class, you can have a method getVersionShortName() to trim it to return 0.10 only.