Roll version 1.4.1
Use riak_core 1.4.1
Merge branch '1.4'

Conflicts:
	rebar.config
Add swap/3 API

Add ability to atomically swap the callback module for a given code
range.  The exact code range must already be registered or an error
tuple is returned.
Merge pull request #31 from basho/feature/rz/swap

Add swap/3 API
Merge branch 'master' into develop
Switch develop back to using tagged riak_pb