Add a basic client type and initializer.
Add a notification type and supporting tests.
Add a basic set of tests for the client type.
Add comments to the client.
Add a method to return the payload as JSON, and add supporting tests.
Refactor the notification type to include other GCM fields.

Includes a bit of general clean-up.
Add a send method to the client that accepts a notification and submits to GCM.

Sample code I just used to send a notification to my Droid:

  c := gcm.NewClient("YOUR_API_KEY")
  n := gcm.NewNotification()
  n.AddRecipient("YOUR_REGISTRATION_ID")
  log.Print(c.Send(n))
Update README.md with installation and documentation information.

Need to update with usage examples in a bit.