Create route for device registration for notifications

[andrewsosa]

• [x] Devices can POST to /api/push/register:

{
    "deviceID": "asdfghjk",
    "platform": 1
}

• Token is the device's unique identifier
• Platform is 1 for iOS, 2 for Android

[andrewsosa]

Implemented in 20dbfbb304aef9e29015711f1565517634037e1c