INT-3064 Change MessageHeaders.Id Strategy

Use `com.eaio.uuid` by default and document how to replace
the default strategy.

Provide JDK and a simple incrementing incrementing implementation.

Add code to detect multiple contexts in the same classloaded using
the same strategy.

Add code to detect multiple IdGenerator beans and emit a WARN
instead of DEBUG, which is the case for no beans.
INT-3064 removed 2 obsolete tests
INT-3082 (S)FTP Remove Deprecated 'cache-sessions'

The 'cache-sessions' attribute was deprecated in 2.1 in favor
of using a configured CachingConnectionFactory to provide more
flexibility, such as setting the cache size.

Remove the attribute from the schemas.

Update tests.

Add docs.

Update Migration Guide on the project Wiki.
INT-3110 Fix JMX Control Bus With SF 3.2.3

Spring 3.2.3 registers MBean operations with parameter names
instead of the JVM default p1, p2 etc based on parameter position
in the method signature.

Since the OperationInvokingMessageHandler matched the supplied
arguments using the p1, p2 etc names, this prevented the control
bus from finding the target method.

Fall back to the old naming scheme based on parameter position
if a matching parameter is not found.

Add a test using a Map payload to supply the named arguments (p1, p2).

Add an ignored test that tests using named arguments (key, channelName).

Test with 3.1.4; remove Ignore and test with 3.2.3.

TODO: remove the Ignore annotation when SF 3.2.3 is the minimum.
INT-1807 Add Mechanism For Headers with TCP

TCP streams have no standard message structure. Therefore, the
TCP implementation previously only transferred the message
payload.

If someone wanted to convey header information, they would have
to write their own wrapper and/or use Java serialization for
the entire message.

This change provides a strategy to allow users to determine
which headers are transferred, and how.

A MessageConvertingMessageMapper is now provided that invokes
any MessageConverter. A MapMessageConverter is provided that
converts the payload, and selected heades to a Map with two
entries ("payload") and ("headers").

A MapJsonSerializer is provided that converts a Map to/from
JSON. Jackson can't delimit multiple objects in a stream
so another serializer is required to encode/decode structure.
A ByteArrayLfSerializer is used by default, inserting a
linefeed between JSON objects.

The combination of these elements now allows header
information to be transferred over TCP. Of course, users
can implment their own (de)serializer to format the
bits on the wire exactly as needed by their application.

INT-1807 Polishing

Add a test that uses a Map MessageConverter with a
Java (de)serializer.

INT-1807: Polishing

INT-1807: Rebased and polished

Change `MapJsonSerializer` to use `JsonObjectMapper` abstraction

Doc Polishing