Ticket #180: FileSystem comparison detects updated targets

- Shine.Configuration.ModelFile supports a way to detect updated
  targets, based on their index or node and device path.  This
  information is used by Shine.Configuration.FileSystem when comparing
  them and reports updated targets and no more removed/added ones.
- Update command was updated thanks to that and slightly improved.
- Few minor bugs in ModelFile code were also fixed.

Change-Id: Idc1ccf8a9818f0e3944415da1e5e7d0664b73b22