Fix CR Newlines:ExpressionEvaluatingMessageHandler

Lines terminated with CR instead of LF
INT-3126: Document DefaultScriptVariableGenerator

JIRA: https://jira.springsource.org/browse/INT-3126
Doc Polishing for the AMQP Support

Documentation for configuring an external listener container in
the inbound endpoints.
INT-3164: Fix Scripting Refresh

Previously, there was no logic to check, if a JSR223 script
was modified should be refreshed from the external resource.

* Fix `RefreshableResourceScriptSource` to take care of refreshing
on call `isModified()`
* Add `scriptSource.isModified()` before getting script text
* Introduce `ScriptSourceFactoryBean` to avoid I/O operations, when
there is need to refresh script resource - `refreshDelay < 0`

JIRA: https://jira.springsource.org/browse/INT-3164

INT-3164: change the refresh mutation logic

Remove factory bean - no longer needed.
INT-3162 Fix AbstractScriptExecutor Thread-Safety

JIRA: https://jira.springsource.org/browse/INT-3162
Merge remote-tracking branch 'upstream/master' into 4.0.0-WIP

Conflicts:
	spring-integration-core/src/main/java/org/springframework/integration/handler/ExpressionEvaluatingMessageHandler.java
	spring-integration-groovy/src/test/java/org/springframework/integration/groovy/config/GroovyServiceActivatorTests.java

Resolve.
Fix Imports After Merge