Rancher machine

[happytreees]

Description

This PR will update the docker-machine to use up-to-date dependencies, and refactor the code

Checklist:

• Have you checked to ensure there aren't other open Pull Requests for the same update/change?
• Have you linted your code locally prior to submission?
• Have you successfully ran tests with your changes locally?

[optik-aper]

Fix typo: instantiate

[optik-aper]

A couple lint issues:

machine/driver/driver.go:253:33: Error return value of `d.addSSHKeyToCloudInitUserData` is not checked (errcheck)
		d.addSSHKeyToCloudInitUserData()
		                              ^
machine/driver/helper.go:97:24: stringintconv: conversion from int to string yields a string of one rune, not a string of digits (did you mean fmt.Sprint(x)?) (govet)
	dockerPortAsString := string(d.DockerPort)
	                      ^

[optik-aper]

Another one:

machine/driver/driver.go:222:16: Error return value of `d.createSSHKey` is not checked (errcheck)
	d.createSSHKey()
	              ^

[optik-aper]

closes #24

[optik-aper]

looks good