INT-2878: MessageGroupStoreReaper's Lifecycle Fix

`MessageGroupStoreReaper` continues to expire `MessageGroups` via `scheduled-task`
when not `running`.

* Add check `isRunning()` to `run()` & `destroy()`
* Additional `MessageGroupStoreReaper` polishing
* Add test-case

JIRA: https://jira.springsource.org/browse/INT-2878

INT-2878: Polishing : PR Comments
Merge pull request #704 from artembilan/INT-2878
INT-2880 Fix System.out Concurrent Race Condition

Gradle may run tests using multiple threads.

Using shared resources (e.g. `System.out`) may produce concurrency issues.

* Remove usage of `System.out`
* Add mocking around `LoggingHandler#messageLogger`.

JIRA: https://jira.springsource.org/browse/INT-2880
Merge pull request #705 from artembilan/INT-2880
INT-2885 Remove DOS Newlines

MessageGroupStoreReaper