INT-2961 Make ARPMH.onInit() Final; Add doInit()

https://jira.springsource.org/browse/INT-2961

onInit() relied on subclasses calling super.onInit() to apply the
advice chain and add the BeanFactory to the MessagingTemplate.

At least one extension (smpp) failed to do this, disabling these features.

Make onInit() final and call doInit() for subclass initialization (no-op in ARPMH).

INT-2961 Polishing

- do not increase visibility of doInit in subclasses.
- remove final modifiers from doInit so user subclasses can participate in initialization if needed.
INT-3180: Fix `FtpParserInboundTests`

JIRA: https://jira.springsource.org/browse/INT-3180

* Change non-existing interface in the config to existing one
* Change `@Test(expected=BeanCreationException.class)` to `try...catch` block
and check the StackTrace for appropriate, expected `Exception`
INT-1362 HTTP Inbound: Additional EvalCtx Vars.

JIRA: https://jira.springsource.org/browse/INT-1362, https://jira.springsource.org/browse/INT-2469

* Add to the `EvaluationContext` of HTTP Inbound Endpoints additional request variables
* Tests and documentation

INT-2669: Mention SpEL variables in JavaDocs

JIRA: https://jira.springsource.org/browse/INT-2669

INT-1362 Doc Polishing
INT-3180 Add s-i-ftp/test to .gitIgnore

Inadvertently added left over test files.
INT-3178 Defer Publishing of TCP Open Event

Previously, the TcpConnectionOpenEvent was published as soon
as the socket was connected, but the TcpConnection was not yet
ready for use.

Defer publishing the event until the connection is fully
initialized and registered with the factory and thus available
for use.

Update the test cases to reflect this behavior.

Since the event is now published by the appropriate concrete
factory implementations, enhance the ConnectionToConnectionTests
to verify proper eventing with both Net and NIO implementations.

INT-3178: Add `theConnection` `ReadWriteLock`

INT-3178 Polishing

- Refactor obtainConnection() into obtainSharedConnection() and obtainNewConnection() for Net and NIO Client factories.
- obtainConnection is now common for these two factories, and overridden by the caching and failover factories.
- ReadWriteLock - double check for shared connection after lock obtained.

INT-3178: Polishing