get rid of the `setimmediate` dependency

Updated NAN to 1.3.0

drop support for Node.js 0.8.x branch

[Suggestion] Use NPM features to ensure correct node version

Fix leak in complete() callback of Database.each()

According to the readme: 
> The sqlite3 module works with Node.js v0.8.x, v0.10.x or v0.11.x (though only v0.11.13 and above).

I propose the engines parameter be updated to be more specific, and that `engineStrict:true` is provided so that the node version should be enforced by npm when running `npm install` (https://www.npmjs.org/doc/files/package.json.html#enginestrict)

another attempt to work around npm and ^ problem - refs https://github.com/npm/fstream/commit/f96c1b338148439e73f7e70ffbdc37e2759dfc68

Conflicts:
	appveyor.yml