optimize: Tach sensors as shared pointers

The fan and trust group objects should utilize shared pointers to the
tach sensor objects. This allows optimizing the storage of additional
attributes associated with the tach sensors.
e.g. An attribute to declare which sensors should be included in the
trust determination.

Tested: Current trust group associations & reactions are unchanged

Change-Id: I249cc7debf467e8275fae7fa157ce97078b40802
Signed-off-by: Matthew Barth <msbarth@us.ibm.com>
5 files changed