BUG-592: Format BI InstanceIdentifier

This is the initial commit which formats the file, adding final keywords
and fixing missing braces, etc. No functional change is made.

Change-Id: Iccef8d2e7d80621ecd7fb077202eb19ecf09727b
Signed-off-by: Robert Varga <rovarga@cisco.com>
BUG-592: introduce InstanceIdentifier.child()

These methods return an immediate descendant of the base identifier.
It turns out these utility methods are open-coded on quite a few places.

Change-Id: I412fb3fcdf538a71fca1d4cb180ac4bc2a9eaeb1
Signed-off-by: Robert Varga <rovarga@cisco.com>
Merge changes I412fb3fc,Iccef8d2e

* changes:
  BUG-592: introduce InstanceIdentifier.child()
  BUG-592: Format BI InstanceIdentifier