Adds Metadata Command/Manager

Adds metadata Manager/Commands.

Example usage of the commands:
```bash
$ sl metadata
usage: sl metadata [-h]
                   
                   {datacenter,backend_mac,primary_ip,network,tags,id,primary_backend_ip,fqdn,user_data,datacenter_id,frontend_mac,provision_state,hostname}
                   ...

Find details about this machine

positional arguments:
  {datacenter,backend_mac,primary_ip,network,tags,id,primary_backend_ip,fqdn,user_data,datacenter_id,frontend_mac,provision_state,hostname}
    datacenter          datacenter name
    backend_mac         backend mac addresses
    primary_ip          primary ip address
    primary_backend_ip  primary backend ip address
    tags                tags
    hostname            hostname
    fqdn                fully qualified domain name
    user_data           user-defined data
    datacenter_id       datacenter id
    frontend_mac        frontend mac addresses
    provision_state     provision state
    id                  id
    network             details about either the public or private network

optional arguments:
  -h, --help            show this help message and exit
```

```bash
$ sl metadata primary_ip
75.126.74.121
```

```bash
$ sl metadata fqdn
host.myserver.com
```

`````bash
$ sl metadata tags
production,frontend
```

```bash
$ sl metadata network private
:...................:.............:.......:..........:
:   mac addresses   :   routers   : vlans : vlan_ids :
:...................:.............:.......:..........:
: 22:22:22:11:11:11 : bcr99.dal05 :  1122 :  213231  :
:...................:.............:.......:..........:
```