Jsig compatibility fixes

Here's change we talked about (https://github.com/grncdr/node-any-db-adapter-spec/pull/7#issuecomment-57160629), but i noticed also some other things that could be changed, so please let me know if it's ok, or if they should be split to separate pull request.

This pull request includes .gitignore by accident. I should have separate it, but forgot about this. It would be helpful to have it when working on changes to spec (and running tests), but if you do not want it, i can split it from this request :).

- Moved quotation marks to conform to the jsig specification.
- Added description of `Continuation`.
- Fixed `Queryable` definition so it uses `ResultSet` instead of `Results` when defining use of Continuation.
- Modified definition of `Query` so it uses `Continuation` instead of in-place definition.