DS-2167: Add Flyway automatic database upgrades to DSpace

https://jira.duraspace.org/browse/DS-2167

Update: This PR is now ready to test for the 4.x -> 5.0 upgrade process. It's "functionally complete".  I'm still working on backporting other migrations scripts in order to auto-migrate from old versions of the DSpace DB.

This PR does the following (unchecked boxes have not been fully implemented yet):

- [x] Integrates dspace-api with (Flyway)[http://flywaydb.org/] for automatic database schema upgrades (Upgrades occur when you startup DSpace - i.e. NO MORE RUNNING SQL SCRIPTS MANUALLY!)
- [x] Refactors our various "database_schema*.sql" scripts into Flyway compatible SQL scripts
- [x] Refactors the XMLWorkflow setup scripts into a Flyway compatible "Java migration". It is kicked off via Java in the new "org.dspace.storage.rdbms.migration.V5_0__XMLWorkflow_Migration" class, and ONLY Run when it's enabled in the workflow.cfg file.
- [x] Reworks/simplifies Unit Tests to just use Flyway to initialize the Unit Testing Database
- [x] Create a Flyway "callback" to automatically reload metadata registry & format registry from config files each time a migration is done
- [x] Create a Flyway "callback" to automatically reindex your data in your search/browse engine of choice each time a migration is completed.
- [x] Remove all Ant related DB scripts, as they are now unnecessary
- [x] Fix Unit Test failure, because the "Metadata 4 All" Oracle upgrade script is unfortunately not compatible with H2 (as it uses "DECLARE" which is throwing an error in H2)
- [x] Backport all older DB migration scripts to help auto-migrate folks from older versions of DSpace
- [x] Other minor cleanup of notes / documentation to no longer require any manual DB upgrades. Doc updates have begun at https://wiki.duraspace.org/display/DSDOC5x/Upgrading+to+5.x (more will be forthcoming as well)

I've done some basic testing of upgrades from 4.0 -> 5.0 database. It seems to work well.

However, fair warning for developers: Testing this WILL REQUIRE you to start with a 4.0 compatible database.  Flyway is not "smart" enough to know if you already manually ran the 'database_schema-4-5.sql" script yet...so it will attempt to run those database schema changes a second time.