Added 'buildSrc' directory as a git submodule to be shared across
all Spring open-source projects. This eliminates the need to maintain
custom Gradle code within Spring Integration directly.
For a brief introduction to git submodules, see
http://speirs.org/blog/2009/5/11/understanding-git-submodules.html
And of course the official documentation is at
http://www.kernel.org/pub/software/scm/git/docs/git-submodule.html
https://git.wiki.kernel.org/index.php/GitSubmoduleTutorial
Conflicts:
spring-integration-twitter/src/main/java/org/springframework/integration/twitter/core/Twitter4jTemplate.java
spring-integration-twitter/src/test/java/org/springframework/integration/twitter/inbound/SearchReceivingMessageSourceTests.java