Sketch: JSON formatters for DSL types
Merge branch 'master' into wip-json
Added JSON formatters for InetAddress, +tests

Also refactored helper methods for constructing valid IPv4 and IPv6 addresses.
JSON format for Inet6Subnet
JSON formatters for Interface and Tunnel
JSON format for NAT.
JSON formatter for DNS.
JSON formatter tests for Doc
Added handling for GET and PUT in HTTP server.
Merge pull request #7 from mesosphere/wip-json

More JSON and HTTP features