Switch to MD-SAL version of test tool data store

Switch to MD-SAL version of test tool data store

The MD-SAL version of the test tool data store offers better
compliance with the Netconf protocol so use it by default.
An argument can be used to switch it off for tests where
performance is needed and correctness is not such as scaling
and performance test suites.

The CRUD suite also needed patching because it was designed
to check for an attribute in the data which is actually not
supposed to be there and was just a test-tool simple
datastore implementation quirk.

The scaling suites were also updated to tell the testtool
to use the simple datastore. These suites need the speed
more than the correctness as they don't do any data
checking.

Change-Id: I8f1d9e18e838169d6249c0998954ba0e0cf9e4fc
Signed-off-by: Jozef Behran <jbehran@cisco.com>