Cleanup, refactoring, add command line flags, changed imports, readme update

[gfieni]

PR overview:

• Remove ssh forwarding parts : not required if you use the Grid5000 VPN.
• Added '--g5k-ssh-private-key' and '--g5k-ssh-public-key' flags to set the ssh keys to use in the provisionning phase and with the command 'docker-machine ssh '.
• Added '--g5k-image' flag to set the image used by Grid5000 when deploying the node.
• Update/cleanup of the README
• First pass cleanup/refactoring of 'driver' and 'deployment' parts of the code.
• Use of github.com remote imports paths to simplify the use of go tools for future maintenance. (The old build/install procedure need to be followed if you plan to test before merging)

[zhangbbo]

I tested on MacOS and Ubuntu 14.04, it works. But when I want to create docker node, always getting (Error: No machine name specified).

Then I add a name "test", always returning (Error setting machine configuration from flags provided: gob: name not registered for interface: "*rpcdriver.RpcFlags").

Docker Client: Version: 1.9.0 API version: 1.21 Go version: go1.4.3 Git commit: 76d6bc9 Built: Tue Nov 3 19:20:09 UTC 2015 OS/Arch: darwin/amd64

Docker-Machine Version: 0.5.0

[mcolmant]

@zhangbbo did you try to update your docker with the last release?

[zhangbbo]

Yeah, I tried. @mcolmant (Error setting machine configuration from flags provided: gob: name not registered for interface: "*rpcdriver.RpcFlags") refers to a bug in old docker-machine, and it has been fixed after 0.5.4

The code works well in MacOS and Ubuntu 14.04

docker version Client: Version: 1.12.0 API version: 1.24 Go version: go1.6.3 Git commit: 8eab29e Built: Thu Jul 28 23:54:00 2016 OS/Arch: darwin/amd64

Server: Version: 1.12.0 API version: 1.24 Go version: go1.6.3 Git commit: 8eab29e Built: Thu Jul 28 23:54:00 2016 OS/Arch: linux/amd64

docker-machine v0.8.0, build b85aac1