* Aadl2Utils.java:
  - Add "getAbsolutePluginPath", method that returns the local file system absolute path for a plugin by its name.

* FileUtils.java:
  - Add following methods:
    - "stringTofile": convert a string object into a file object.
    - "getContainningDirectory": return the parent directory of a file object.
    - "getSubDirectories": return recursively the sub directories of a directory.