HDFS: initial working example + additions and dirty hacks to Fabric8 code to support recursive properties replacement. Added a couple of TODOs

HDFS: initial working example + additions and dirty hacks to Fabric8 code to
support recursive properties replacement. Added a couple of TODOs. A future refactoring is required to move `substituteEnvironmentVariableExpressions` static method to a common utility class that can be imported without introducing circular dependencies at maven level 


![screenshot from 2014-06-13 18 30 58](https://cloud.githubusercontent.com/assets/1520602/3285079/e27a5476-f534-11e3-9312-443e23388873.png)