Update public IP setting

[VMTrooper]

Instructions should state elastic_ip and not associate_public_ip

[davidski]

I disagree with this change. associate_public_ip is the preferred way of getting a public IP on AWS VPC. associate_public_ip is only available under the master branch of vagrant-aws (see the multiple issues commenting on this here on GitHub).

We really need a new vagrant-aws release to help out users that continue to get confused on the differences in the published docs and what they get via vagrant plugin install not to mention getting this feature out for folks without asking them to jump through hoops of building the plugin from scratch. Can anyone comment on when we'll finally get a new release?

[VMTrooper]

Thank you for the clarification. Perhaps, it would be better for the doc to say something like associate_public_ip for version 0.x+ and elastic_ip for older releases?

As you stated, it was a bit confusing since I'm not building the plugin myself.

[davidski]

If we'd get a release out as has been asked about for 4 months over in #206 this would all be moot. Just saying. 😉

[rtyler]

@VMTrooper is this pull request still actually valid with the fix for #206 in the 0.5.0 release?

[VMTrooper]

This pull request is no longer valid with the updated release. apologies for not closing it sooner.