Allow for the HWADDR configuration line to optionally disabled

[divansantana]

Unfortunately in some really unsual environements, the MAC address may not be persistent. In some environments there may even be a valid reason for the MAC address not being persistent.

In our z/vm environment a guest may move from one LPAR to another and boot up with a different MAC address. Hence it's useful to make the HWADDR line in the network config file optional. This doesn't cause an issue, since the SUBCHANNELS line exists in this case.
Ideally our z/vm environment would be configured correctly, in that the MAC address would be persistent but that is another issue altogether.

[razorsedge]

Would it be possible to update the README.md, add some rspec tests, and to resubmit this PR against razorsedge:develop?

[anders-larsson]

@divansantana @razorsedge Would it be possible to drive this pull request forward? Would love to have this functionality implemented.

Thanks.

[Phil-Friderici]

Hej @razorsedge,
I think that #69 is a more complete successor of this PR. It not only features the README update but also brings in full spec tests as addition.

Please have a look at @anders-larsson's PR.
If there should be missing anything, I am happy to contribute whatever is needed :)

Thanks & have phun
Phil

[razorsedge]

I will look at all of these PRs tomorrow at the Contributor Summit.