Added support for branch node to batch messages.

Collects the tuples into a dict with the key as the type, and the value
as the list of tuples of that type. Then each group can be notified
together, rather than sending a singleton list.
Added bert.erl as a dependency.

Use the command `rebar get-deps' to clone into the repository.

Workflow now changes to
  (a) dialyzer -I include --src src deps/*/src
  (b) erl -pz ebin deps/*/ebin
Encode data using BERT specification.

Refer to bert-rpc.org for more information.
Merge branch 'bert'