Azure: allow PNP communication using resource manager

[vinseon]

Unlike Amazon, Azure doesn't provide a complete metadata service nor automatic DNS setup for the VMs.
Therefore, a VM doesn't known its own public IP address and PNP communications can not be fully established between server and nodes.
Solutions could be to:

• Manually setup a DNS using Azure API and specify it to the VM by script injection
• Retrieve the VM public IP address using API and specify it during script injection
• Let the VM discover its own public IP address by using public service like curl ipinfo.io/ip (from script injection OR init script)

[vinseon]

Solved from Fabien's improvement over PNP protocol (ow2-proactive/programming#1334).
The public IP is now given through PNP communication along with the private IP.
To start the scheduler/node behind a NAT, we just need to add the following extra parameters;
-Dproactive.useIPaddress=true -Dproactive.net.public_address=$(wget -qO- ipinfo.io/ip)