Hardware List Filters

Adds most filters for `sl hardware list` as `sl cci list`. There were issues with filtering based on CPU and memory so those were excluded. This support is added to the CLI command and the hardware manager.

Also adds sort option to match `sl cci list`.

```
$ sl hardware list --help
usage: sl hardware list [options]

List hardware servers on the acount

Examples:
    sl hardware list --datacenter=dal05
    sl hardware list --network=100 --domain=example.com
    sl hardware list --tags=production,db

Options:
  --sortby=ARG  Column to sort by. options: id, datacenter, host, cores,
                  memory, primary_ip, backend_ip

Filters:
  -H --hostname=HOST       Host portion of the FQDN. example: server
  -D --domain=DOMAIN       Domain portion of the FQDN. example: example.com
  -d DC, --datacenter=DC   datacenter shortname (sng01, dal05, ...)
  -n MBPS, --network=MBPS  Network port speed in Mbps
  --tags=ARG               Only show instances that have one of these tags.
                           Comma-separated. (production,db)

For more on filters see 'sl help filters'

Standard Options:
  --format=ARG           Output format. [Options: table, raw] [Default: table]
  -v --verbose           Verbose Output
  -C FILE --config=FILE  Config file location. [Default: ~/.softlayer]
  -h --help              Show this screen
```