Add a "raw" parser concept, also add sync device platform support for hp_comware

[jeffkala]

Key to getting hp_comware supportred was to support a "raw" parser, there was no other command/json/template option besides grabbing the output directly from a configuration command. This is also going to be very valuable for other platforms where certain data fields can be more easily extracted by just running a raw command and not requiring json output.

Example

  hostname:
    commands:
      - command: "display current | include sysname"
        parser: "raw"
        jpath: "raw"
        post_processor: "{{ obj.lstrip().split(' ')[1] }}"

[jeffkala]

fixes #249