(2/7) RFC79: Make study_es_0_inc data pass validation

[forus]

• document how to load study_es_0 study
• Remove SpringUtil.initDataSource(); from multiple classes as it was causing not used services to fail during initialisation
• organise imports (remove unused, no wildcard imports) for the classes that lost SpringUtil.initDataSource(); statement.
• include into the test data (seed_mini.sql) genes that are used by study_es_0 data.

Please review https://github.com/cBioPortal/cbioportal-core/pull/43 next.

Please note, to avoid the costly process of rebasing all pull requests (PRs), all feedback will be incorporated into the final PR.