Refactor/allow sitewise keys

[rharriso]

• Allow targets to define there own keys (use global if not definted)
• use standard lib json encoding

target.json example

{
    targets: [
        {
            "user": user,
            "ip": ip,
            "key": "key file",
        },
        {
            "user": user,
            "ip": ip
        }
    ],
    "key": "global key file"
}

[emirozer]

Thanks for the PR, i will test and give feedback soon 👍