Bug 981: Fixed accidental shaddowing of data in Data Change Event.

Not all Normalized DOM InstanceIdentifier has their counterpart
in Binding-Aware representation. Added explicit check to
detect mixin instance-identifiers which could lead to
incorrect deserialization into maps and shadowing parent data.

Change-Id: I66166f50c636ce0dfcd962efac7fc488da622336
Signed-off-by: Tony Tkacik <ttkacik@cisco.com>
Bug 508: Improved error reporting for failed canCommit phase.

Original implementation did not provide enough information
when transaction precondition failed.

Introduced new Exception DataPreconditionFailedException
which captures fail reason and path to subtree
for which precondition failed.

This helps debug accidental overwrites / conflicting
writes between transactions.

Change-Id: I0133fd3fdb8e6492bf457dab7b20efa67fd6e2af
Signed-off-by: Tony Tkacik <ttkacik@cisco.com>
Merge "Bug 981: Fixed accidental shaddowing of data in Data Change Event."
Merge "Bug 508: Improved error reporting for failed canCommit phase."