Proposal for dnsmasq:options support

[kubealex]

I wrote a small addition to optional fields without complicating the parsing with XML Namespace support.

The dnsmasq_options field is a simple list of string and it works in an analogue way as autostrart and bridge.

Example

  dnsmasq_options = [
    "server=/test.example.com/192.168.200.1",
    "test"
  ]

Correctly ends up in:

  <dnsmasq:options>
    <dnsmasq:option value='server=/test.example.com/192.168.200.1'/>
    <dnsmasq:option value='test'/>
  </dnsmasq:options>