Add support for adding SQL query overrides to associated databases

Certain databases that have internal optimizers such as Derby and Splicemachine allow for passing overrides to the SQL query via specific comment structures:
In Derby: pass in `--DERBY-PROPERTIES constraint=cons1` after the FROM clause
In Splicemachine: pass in `--SPLICE-PROPERTIES constraint=cons1` after the FROM clause

The proposed fix for this is to modify [QueryParser.java](https://github.com/twosigma/beakerx/blob/master/kernel/sql/src/main/java/com/twosigma/beakerx/sql/QueryParser.java#L87)

To check for a list of accepted "overrides" and set `boolean mustBeDeleted` (the third parameter) to false if so.

I am happy to make the change and create the PR if desired.