Fix reading JPEGs from a TPK. Do not truncate the buffer before base64 encoding.

Also fix package version to work with current NPM. Required before npm install would run.

Here's what the map looked like before. The black stripes were actually missing rows from each tile (on a black background).

![2014-10-14_13-55-43](https://cloud.githubusercontent.com/assets/25374/4635803/48d0282a-53dd-11e4-861d-ca6a0914c90a.png)