Now always return an object from calls to the PushBullet APIs, even for errors.

Previously, an error response from the PushBullet API would have resulted in a modified JSON string that could not be parsed as JSON (Chrome 39, beta). Now it returns an object with an "error" property, the value of which is the parsed error object from PushBullet. If no JSON error was returned from PushBullet, there will at least be a "response" property with the raw value of the AJAX response. Additionally, an "httpStatus" property will be present in the object returned (or thrown) to the caller when the HTTP status code is !== 200.