Add a gomkv folder to get correct binary name

Move main.go into gomkv subdir
Ignore artifacts
Pass by HandBrakeMeta by reference not value

- fix bug caused by pass by value instead of ref
- convert fmt.Printf to debug func so you can
  turn it on/off later
- add audio and subtitle maker functions
- rename parseOutput -> ParseOutput so it can be called publically
- move creation of subtitle and audio meta structs to
  scanners. Otherwise empty subtitle and audio sections would
  falsely create entries.
- remove aac, needs a difference scanner. Target is still AC3 and DTS
- fix an off by sign bug in parsing channel info
- add a new unit test with different metadata and no subtitle
Add a basic wrapper around os.exec

Return stdout and stderr to caller.
Flesh out gomkv cli tool

- Add basic integration
- invoke HandBrakeCLI
- pass output to parser
- dump parsed output to console