Bug 3195: Cleanup on error paths and error handling

Bug 3195: Cleanup on error paths and error handling

Modified ShardCommitCoordinator#handleBatchedModifications to remove the
cohortEntry from the cache if the total messages sent doesn't match the
total received.

With recent yangtools changes, write and merge on a DOM tx can throw
unchecked exceptions if he data is invalid. Modified the front-end
local tx path to catch unchecked exceptions in LocalTransactionContext
and propagate to the LocalThreePhaseCommit to immediately fail the
ready.

Similarly modified ShardCommitCoordinator#handleBatchedModifications to
handle unchecked exceptions from applied operations and propagate when
the tx is readied.

Added unit tests to cover these cases.

Also, modified LocalTransactionContext#readyTransaction to handle
unchecked exceptions from the DOM tx ready.

Change-Id: Ib6fe6e04b8626bf996cfabfe74da780f05ce838a
Signed-off-by: Tom Pantelis <tpanteli@brocade.com>