AFWA-8 AFWA-14 WIP: Added server code to handle GCM. Need to test.

Major changes:
 - Added package node-gcm
 - Add parameter cloud to register HTTP GET to distinguish between ADM and GCM.
  - &cloud=ADM for ADM registration ID
  - &cloud=GCM for GCM registration ID
  - Set in redis a user object
    { userId: Encoded email, cloud: ADM/GCM, endpointArn: ADM/GCM registration ID }
 - Change notificationTransport to admTransport.
 - Add gcmTransport for sending GCM messages.
  - Config file (git-ignored) to contain GCM API key.
   - config-example.js shows how to use.
 - Change sendNotification to sendADM.
 - sendGCM to send message via GCM.
 - On call to sendADM or sendGCM depending on redis cloud value.