Post SPR-8804 optimizations: better use of HC 4.3 APIs
Merge pull request #350 from ok2c/httpclient_4_3

* httpclient_4_3:
  Post SPR-8804 optimizations: better use of HC 4.3 APIs
Use correct header for version in CONNECTED frame

Previously, the negotiated version was included in the CONNECTED frame
using the accept-version header. This is incorrect. The version
header should be used.
Add StompProtocolHandler tests
Added 'zone' attribute to @Scheduled

Issue: SPR-10456
Added conversion support for Java 8's ZoneId class and the 'of' method convention

Issue: SPR-1528
Polishing
Add option to remove path ext in ServletUriCompBuilder

Issue: SPR-10272
Add basic javadoc to spring-messaging annotations
Add support for Ping and Pong WebSocket messages

Issue: SPR-10876
Release version 4.0.0.M3
Increment version to 4.0.0.BUILD-SNAPSHOT
Stomp codec

Previously, the broker relay's TCP client used Reactor's built in
delimited codec as part of its parsing of STOMP frames. \0 was used as
the delimiter. This worked for most STOMP frames but, crucially,
not for frames with a body that contained \0: when such a frame was
received it would be truncated.

This commit adds a custom codec that parses STOMP frames more
intelligently. It honours the content-length header allowing it to
correctly parse frames with a body that contains \0. The codec largely
delegates to two new classes: StompEncoder and StompDecoder. For
consistency, code that previously used StompMessageConverter has been reworked to use these new encoder and decoder classes.