INT-3223 Tail - Exclusive Attributes

JIRA: https://jira.springsource.org/browse/INT-3223

Disallow 'native-options' if any of the attributes
required for the Apache implementation are specified.
INT-3223 Polishing

JIRA: https://jira.springsource.org/browse/INT-3223

Don't use primitives in Tail factory bean setters so that the placeholders
for attributes that force the Apache implementation can resolve to "".

Test for an empty string in native-options and don't set.
INT-3231: Fix Tail setters types for SPR 3.1.x

JIRA: https://jira.springsource.org/browse/INT-3231
INT-3228: Remove Previous versions' Deprecations

JIRA: https://jira.springsource.org/browse/INT-3228

Remove elements that were deprecated in earlier
versions; see the migration guide for more information

https://github.com/spring-projects/spring-integration/wiki/Spring-Integration-2.2-to-3.0-Migration-Guide

INT-3228: Revert FileTransferMH#setTempDirectory
INT-3221: Deprecate MessageTransformingCI

JIRA: https://jira.springsource.org/browse/INT-3221
INT-3220,INT-3224: Fix Twitter & Channel docs

JIRA:
https://jira.springsource.org/browse/INT-3224
https://jira.springsource.org/browse/INT-3220
INT-3221 Polishing

Remove unused import.

JIRA: https://jira.springsource.org/browse/INT-3221
Added support for 'load-balancer-ref' attribute of the 'channel' element. Added tests and updated documentation