Network Information sample

@devnook & co., please take a look if you have the chance.

Support for the Network Information API is currently only available using Chrome 38 (current dev channel) on an Android, iOS, or ChromeOS device. The sample falls back to the `unknown` network type on unsupported devices.

You can view a working demo using a supported device at https://rawgit.com/jeffposnick/samples/network-information/network-information/index.html