Handle NoNode error from create Op in ZkOpList

Handle the case where NoNode exception is thrown because a path
is created or updated after it's deleted.  ZkOpList in that case
massages the internal data structures that store the Op objects
so that NoNode exception would not be thrown.

Change-Id: Ic0cf3e7f011478cd6b906598a062c1305b6ea70e
Fixes: MNA-2
Merge "Handle NoNode error from create Op in ZkOpList"