LU-3589 tests: Access changelog record FIDs by name.

LU-3589 tests: Access changelog record FIDs by name.

Update sanity test_160 to make it parse changelog records
in a more robust way. Access target and parent FIDs by name
instead of relying on their position on the line.

Signed-off-by: Henri Doreau <henri.doreau@cea.fr>
Change-Id: Ib5836a8e624f04a971b80f9ff9b9e978bbff7bee
Reviewed-on: http://review.whamcloud.com/6998
Tested-by: Hudson
Reviewed-by: Jian Yu <jian.yu@intel.com>
Reviewed-by: James Nunez <james.a.nunez@intel.com>
Tested-by: Maloo <whamcloud.maloo@gmail.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>