Change put/merge methods to be type-safe in WriteTransaction

Removed declaration of put/merge methods from the common
AsyncWriteTransaction interface.

Defined put/merge methods in the derived Binding and DOM interfaces.
The Binding methods were made type-safe.

Javadoc usage/examples for the methods was put into the
AsyncWriteTransaction class docs and is linked to by the derived
interfaces.

This change is source-code compatible - no client code needs to change
(unless a client actually is incompatible path and data).

Change-Id: I779f6477f1c98e299c5d559043da612be97bfbe6
Signed-off-by: tpantelis <tpanteli@brocade.com>