General cleanup in spring-batch-samples

* Delete unused classes, files, misc ide files
* Cleanup checkstyle/pmd/findbugs reports
* Add @Override as needed
* Remove schema versions in xml configs
* Remove unused imports
* General tidying
* Cleanup deprecated jdbctemplate methods
* Fix @Ignored OrderItemReaderTests test
BATCH-2196: Document JobScope

Updated documentation to reflect information gathered from Javadocs