* INT-4322: Log merged global properties on startup
JIRA: https://jira.spring.io/browse/INT-4322
Now we have DEBUG message in logs like this:
```
Spring Integration global properties:
spring.integration.endpoints.noAutoStartup=fooService*
spring.integration.taskScheduler.poolSize=20
spring.integration.channels.maxUnicastSubscribers=0x7fffffff
spring.integration.channels.autoCreate=true
spring.integration.channels.maxBroadcastSubscribers=0x7fffffff
spring.integration.readOnly.headers=
spring.integration.messagingTemplate.throwExceptionOnLateReply=true
```
* Also register a `mergedIntegrationGlobalProperties` bean on a first
`IntegrationContextUtils.getIntegrationProperties()` call to avoid a
new `Properties` object on each call
* * Fix `TestUtils` to register a `BeanDefinition` instead of `registerSingleton()`
and an explicit `afterPropertiesSet()` call
* * Document mentioned changes
* Some polishing for `whats-new.adoc`
8305c6fec3