Explictly set root project name in settings.gradle

Bamboo CI server checks out into a directory named
'checkout', instead of a directory named 'spring-integration'
as would be expected.  Root project naming defaults
to the name of the containing directory, so it becomes
important to be explicit.

settings.gradle

@@ -14,6 +14,8 @@
  * limitations under the License.
  */
 
+rootProject.name = 'spring-integration'
+
 include 'docs'
 include 'spring-integration-core'
 include 'spring-integration-event'