Batch Integration to Batch

Move `spring-batch-integration` from `spring-batch-admin` to `spring-batch`, retaining history.

Used

    git filter-branch -f --tree-filter 'rm -rf pom.xml release-process.md spring-batch-admin-sample/ src/ README.md spring-batch-admin-manager/ spring-batch-admin-resources/' --prune-empty batch-integration-to-batch


Note: maven build still uses `spring-batch-admin-parent/pom.xml` which was also retained.

Needs to be integrated into the main batch build.