multi-instance support

[pjutard]

What I'm thinking for solving this issue is the following:

1) Add support for adding and removing instances from the CLI. 2) As all instances will be behind the same load balancer, the post-commit hook will hit allways one of those instances, so we should make that instance to propagate that POST to all the rest of the instances in the same role. For that purpose we can use the Azure SDK for Node.js for:

azure.RoleEnvironment.getRoles(function(error, roles) {
    if(!error){
        // You can get information about "instance1" of "role1" via roles['role1']['instance1']
    } 
});

[pjutard]

We should also think about how to handle the logs.

[tjanczuk]

There are several things that need to happen for multi-instance support:

• git azure init must allow --instances to be greater than 1
• during git azure init, the check of the status of the deployment must be modified to account for multiple instances
• after git-azure-init, the IP addresses of all backends must be stored in git config
• figure out a way to SSH/RDP to individual backend machines
• the backend that receives a post receive hook must propagate it to other backends; the same applies to git azure reset
• the backend that receives WSS request for logs must harvest the consolidate the logs from all other backends; this mechanism must be resilient to backend recycling, including changes in IP addresses

This will take several commits, I will be doing the work in a scaleout branch.