INT-2830 Resolve Class Tangle

* MessageGroupStore <-> MessageGroupCallback
  - Change callback to be an inner interface of the MGS.
* INT-2829 Fix Class Tangle in IP Module
  - 3 way tangle between TcpSender, TcpConnection, TcpMessageMapper
  - Clean up interfaces (remove setters); add top-level support classes for TcpConnection, TcpConnectionInterceptor.
* INT-2829 Remove TCP Package Tangle
  - tcp.connection <-> tcp.connection.support
  - Remove ...connection.support package - move classes to ...connection.
Merge pull request #719 from garyrussell/INT-2829

* garyrussell-INT-2829:
  INT-2830 Resolve Class Tangle
INT-2126 Add TcpConnection Event Publisher

TcpConnectionEvent for OPEN, CLOSE, EXCEPTION.

<int-ip:tcp-event-inbound-channel-adapter />
INT-2871 Provide Mechanism to Find TCP Connections

https://jira.springsource.org/browse/INT-2871

Add getOpenConnectionIds() to Abstract Connection Factory

Also add closeConnection(String connectionID)
INT-2877 TCP Extension Improvements

Improvements to make extension easier.

* Add setCustomHeaders() to mapper.
* Add mapper to connection factory namespace parser.
* Add plumbing for stateful Deserializers.
INT-2872 Remove Deprecated Items in ip Module

- pool-size Attribute
- setScheduler
- TcpSendingMessageHandler.getConnection()

Deprecated attribute on TCP Connection Factory.