BATCH-2144 Convert Spring Batch to use Gradle

* Use Gradle 1.11
* Remove SpringSource references
* Update JavaDoc overview
* Update Jacoco conf + Add license/manifest files
* Addresses also BATCH-2187
* Update a number of unit tests to not be ignored

Jira: https://jira.springsource.org/browse/BATCH-2144
BATCH-2144 - Merged Michael's changes

* Merge PR https://github.com/ghillert/spring-batch/pull/1
* Update Spring Integration dependency to 4.0.0.RC1
* Update docbook-reference-plugin to 0.2.8
BATCH-2144 Fix reference doc header
BATCH-2144 Add Chris Schaefer as dev to `publish-maven.gradle`
BATCH-2144 Remove `generateSql` task from `build.gradle` (Root, duplicate with `spring-batch-core/build.gradle`)
BATCH-2144 Add test inclusions/exclusions for tests to `build.gradle`
BATCH-2144 Exclude long running test (same behavior as Maven)

* `$ mvn clean install -P bootstrap,all` does not run all tests. Exclude those additional tests from the Gradle build by default. They can be activated by providing the the `alltests` parameter, e.g.: `./gradlew clean build -Palltests`
* Execute the exact same tests as the Maven build
* Improve execution speed of Gradle build
BATCH-2144 Ensure that Gradle version of Spring Batch compiles with Java 8
BATCH-2144: Removed OSGi ApplicationContextFactory