Blindly import the chrome.bluetooth API.

From https://code.google.com/p/chromium/codesearch/#chromium/src/chrome/common/extensions/api/bluetooth_low_energy.idl
Convert callbacks to Promises.
Add sections so ReSpec's IDL formatting makes sense.
Merge pull request #2 from jyasskin/from-chrome-api

Import an initial GATT interface from the chrome.bluetoothLowEnergy API

Many things about this will need to change, but it provides a starting point.