Binary deployment with node-pre-gyp

This replaces the [homegrown solution for binary deployment](#192) with a better and more generic approach using [node-pre-gyp](https://github.com/springmeyer/node-pre-gyp).

Users installing node-sqlite3 won't need to know about this switch, but will help with the development and faster publishing of binaries going forward.

 - requires the min Node version to be `>= 0.8.0`

### Before merging

 - [x] - Update the wiki page on binaries: https://github.com/mapbox/node-sqlite3/wiki/Binaries
 - [x] - Push `v2.2.0-alpha` binaries and ping @flip111 to help test (#244)
 - [x] - Test node-webkit
 - [x] - Test on windows

### After merging

 - [ ] - Tag v2.2.0 and publish binaries