tools: owners: initial parsing of OWNERS file
tools: owners: initial parsing of OWNERS file

Tested:

```
$ tools/owners reviewers
{"reviewer": "geissonator@yahoo.com", "state": "REVIEWER"}
{"reviewer": "joel@jms.id.au", "state": "REVIEWER"}
{"reviewer": "cbb7353e6d953ef360baf960c122346276c6e320@stwcx.xyz", "state": "REVIEWER"}
{"reviewer": "andrew@aj.id.au", "state": "CC"}

$ tools/owners reviewers --push-args
r=geissonator@yahoo.com,r=joel@jms.id.au,r=cbb7353e6d953ef360baf960c122346276c6e320@stwcx.xyz,cc=andrew@aj.id.au
```

Signed-off-by: Patrick Williams <cbb7353e6d953ef360baf960c122346276c6e320@stwcx.xyz>
Change-Id: I145bd065dff101776c733fddb26fea4f324dd100

openbmc/openbmc-build-scripts,openbmc/openbmc-build-scripts