Pull repo authorization info from .netrc

Using the [.netrc](http://linux.die.net/man/5/netrc) file will allow you to use an [OAuth token](https://github.com/blog/1270-easier-builds-and-deployments-using-git-over-https-and-oauth) to authenticate for private repositories without hard-coding in the user credentials into the component.json. This is what mine looks like:

```
machine raw.github.com
  login {MY_GITHUB_OAUTH_TOKEN}
  password x-oauth-basic
```

It has several benefits:
* better for security
* you don't have to add another remote; just use it as if it were public
* share the repos across an organization with different creds
* revoke access on any token if compromised