Use CoreOS beta channel
change update channel to beta
Merge pull request #2 from EqualMedia/change-update-channel-to-beta

coreos-vagrant: Change update channel to beta
Bump memory to 8Gb.
Added iptables rule to redirect AWS Metadata service.
Updated ntpd config to allow it to update the time
no matter the lag.
Added /Users NFS mount if running on OSX to simplify using docker locally.
fixup! Bump memory to 8Gb.