Server should support config server

As a developer, I would like to store the configurations outside the project.

A few changes are required before that:
1) Server should support all in one config file (xml|yalm)

The config file should support all configuration available at `server.sh -h`

Example: config.yaml

bind-address: localhost
server-config: infinispan.xml

In this case, I am going to start the server with: server.sh --file-config=config.yaml

2) In order to have all configuration in one place, as a developer I would like to have the following:

infinispan: 
  config: 
    server: 
      git: 
         uri: https://github.com/infinispan/config-repo
         username: foo
         password: foo123
bind-address: localhost
server-config: infinispan.xml

Different authentications should be supported like:

uri: git@gitserver.com:infinispan/repo1.git
ignoreLocalSshSettings: true
hostKey: myKey
hostKeyAlgorithm: ssh-rsa
privateKey: |
     -----BEGIN RSA PRIVATE KEY-----
     bLaH
     -----END RSA PRIVATE KEY-----

It allows the team have a centralised configuration files with formal approval (aka PR).