refactor DataSourceAdapter
  add the unique fetch() public interface to DataSourceAdapter
  merge mysql and msaccesss db handling
  unify all URI definitions to <scheme>://<user>:<pass>@<host><path>[?<query>]
  drop CommandUtils, refactor IO utilities into the new IOUtils class
  drop mysqli support
  update ExportCommand and BaseSchemaMapper with the simplified method.
Merge remote-tracking branch 'origin/master'