Better OS X client instructions in README.md

The instructions on exporting DOCKER_HOST weren't quite right. It is probably better to just reference the official docs.
Merge pull request #37 from simonista/patch-2

Better OS X client instructions in README.md
Fix typo

Doh! :)
Merge pull request #38 from simonista/patch-3

Fix typo
updating doc
Merge branch 'develop'
readme update
Chang gitgnore
Headless activation
Added support of Parallels provider
Merge pull request #41 from legal90/master

Added support of Parallels provider
No need for the build-iso script now
We don't need to track any iso
Adding auto_correct to NAT rule for docker daemon
Moving packer virtualbox provider to headless for IC build
Moving box build to official b2 build ans using vagrant 1.6 brand new docker provider
Adding version constraint to README + updating build process
merge docker-build