README improvements

[stanlemon]

I removed the 'reload' reference in the sync section because it is not implemented for the aws provider.

I also added notes on how to get around the tty issue for Amazon Linux AMIs. I realize this is image specific, but as this provider does not work out of the box with the stock/default AMIs that are most common to AWS this seems like it would be helpful information for those getting started.

[pidah]

The sudo tty workaround in the pull request worked sometimes and failed other times. I have also tried passing similar user_data scripts in the past to the Amazon Linux AMI's with varying results, don't know why.

[stanlemon]

I have seen some oddities on this front too - almost like the cloud init data hasn't finished executing or something like that. Not sure if there is a way to sleep or some way of issuing a callback to vagrant to trigger init of the provisioning process.

[pidah]

perhaps some race condition..not sure...I have resigned to using custom ami's or ubuntu images which seem to just work

[tralamazza]

PR #85 implements the disable tty for amazon linux.
The problem is, these are super specific settings.

[tralamazza]

I will close this and move possible fixes to a wiki page. Our README is already gigantic.