Add GCM registration ID in Device attributes

Signed-off-by: Ricardo Leitão <rleitao@lqd.io>
Use UTF-8 encoding on API requests

Signed-off-by: Ricardo Leitão <rleitao@lqd.io>
Add _pauseSession and _resumeSession events

Signed-off-by: Ricardo Leitão <rleitao@lqd.io>