INT-2867: Add Script Support to inbound-c-a

* Add `<script>` and `<expression>` to `<int:inbound-channel-adapter>`
* Refactoring for `DefaultInboundChannelAdapterParser`
* Introduce `ScriptExecutingMessageSource` to allow scripts' `MessageProcessor`
implementations work as a source for polling endpoint

JIRA: https://jira.springsource.org/browse/INT-2867

INT-2867: documentation

In addition the tests for Lifecycle attributes

Polishing
DOS->Unix NewLines in Several Core Files