Bug 2857: Tied pre-existing implementation to BindingCodecTree.

Bug 2857: Tied pre-existing implementation to BindingCodecTree.

BindingCodecTree provides public view into backing structure
of binding-data-codec, which was designed and already implemented
as data tree.

By exposing these power-users could build their own
Binding to DOM adapters, where they could customize some aspects
of serialization or precache over-used codecs in order
to speed up performance.

Change-Id: I827eb6014b28d0b6d4256b677ee56d3081ff80b0
Signed-off-by: Tony Tkacik <ttkacik@cisco.com>