flattened the patch by Larry Weya: append values when the column already exists: https://github.com/StanfordHCI/datavore/pull/1

As noted by Larry: "Doesn't seem to work with aggregate queries on nominal types."
gitignore + gitattributes
- rigorous application of coding standard where each line contains at most a single statement in order to ease debugging / breakpointing (particularly in Chrome)

- documented two @private functions
provided a complete implementation for dv.table.addColumn() which supports appending to the existing data, while you may even change the type when appending values to the table (though this would a rather costly operation as all the existing values must be reprocessed alongside the appended data); this fixes the patch by Larry Weya.
update the demo page to be interactive - code copied off the Datavore site
fix b0rk due to the table column being assigned the incorrect index. (This error was clearly visible in the SPLOM example.)