PRD-4855 - Kettle datasource now no longer queries database for getting row-metadata.
PRD-4855 - Pentaho Metadata now computes columns for design-time without hitting the database .
[CLEANUP] - Split overly long method into smaller chunks.
PRD-4855 - Extract interface from design-time data-schema, so that we can use proxy classes for async access.
PRD-4855 - Adjust code to use interfaces instead of concrete implementation as much as possible.
PRD-4855 - Start of akka based asynchronous datasource handling
PRD-4855 - Finished asynchronous handling of data sources. Long queries no longer block the report and tree and field selector updates on the fly when the data comes back.
PRD-4855 - Reroute wizard materialization queries to faster design-time mode.
Merge pull request #448 from tmorgner/PRD-4855

PRD-4855 - Faster designtime queries and asynchronous query handling in PRD