PEP8
Add user friendly short summary during vm creation
allow calls to shell(), with no shell.

easier to build variable argvs with commands
refactor argv building in iaas.ssh()
implement --login, -l or user@host for ssh

when both -l and user@host are provided, mimic ssh behaviour
rename "shell" to execute

just because shell(cmd, shell=True) sounds wrong
(related to dccbe29)
update documentation about option parsing

for docker subcommand, explicit usage of a -- separator
Improve summary message during vm creation
Merge pull request #8 from kalou/docker-doc

update documentation about option parsing
login parameter for vm creation is now really optionnal
Merge branch 'github_master' into stable
add documentation for the ssh login parameter
Merge pull request #7 from kalou/ssh-opts

Improve vm ssh command to handle login@vm parameter or --login
Apply PEP8, fixes docstrings and remove unused imports
Fixes ssh call parameters after vm creation and summary before creation
Fixes shell command execution parameter kwargs
Fix code style for manpage commands in README
Merge pull request #9 from webcracy/patch-1

Fix code style for manpage commands in README