More Features for Query Execution

  * Limit and Offset for Queries as HTTP Params (like the query)
  * SimpleTableScan has ofDelta flag to restrict the search to the delta
  * Added generic expression for simple delta searches
  * Appending to delta is now really thread safe
  * Added auto increment field as Serial when using JsonTable to create tables
  * affectedRows and generatedKeys as fields in the meta data of the query
  * Adding serial fields for auto_increment in JsonTables
Merge pull request #156 from hyrise/feature/value_scan_for_delta

More Features for Query Execution