feat(throwHelp): far more useful error messages

[msimerson]

Before

> new RR.A({ owner: 'matt.simerson.', type: 'A', ttl: 3600 })
Uncaught Error: A: address is required
    at A.setAddress (file:///Users/matt/git/nictool/dns-resource-record/rr/a.js:12:21)
    at new RR (file:///Users/matt/git/nictool/dns-resource-record/rr.js:25:19)
    at new A (file:///Users/matt/git/nictool/dns-resource-record/rr/a.js:7:5)

After

> new RR.A({ owner: 'matt.simerson.', type: 'A', ttl: 3600 })
Uncaught Error: A: address is required

Example A:
{
  'owner' => 'test.example.com.',
  'type' => 'A',
  'ttl' => 3600,
  'class' => 'IN',
  'address' => '192.0.2.127'
}

see RFC 1035

    at A.throwHelp (file:///Users/matt/git/nictool/dns-resource-record/rr.js:133:11)
    at A.setAddress (file:///Users/matt/git/nictool/dns-resource-record/rr/a.js:12:20)
    at new RR (file:///Users/matt/git/nictool/dns-resource-record/rr.js:27:19)
    at new A (file:///Users/matt/git/nictool/dns-resource-record/rr/a.js:7:5)