Filter is optional, other cleanup

* Filtering now adheres to "filterable" on the column.
* Added column defaults to extend from so that all the options are present if not overriden.
* Other general code cleanup
Merge pull request #11 from mrkrstphr/filter-is-optional

Filter is optional, other cleanup
Implemented column sorting
austin is stupid
Merge pull request #12 from mrkrstphr/sorting

Implemented column sorting