Add Dockerfile

[dgarros]

I created a new Dockerfile inspired by @ntwrkguru's work to automatically build a docker container for the ansible modules, it's very similar to what we have done with Pyez

@vnitinv, please review

[ntwrkguru]

Now that it's been merged, we need to update the repo on the Hub. @dgarros, I couldn't figure out how to change the repo. Any clue?

[dgarros]

Done,
BTW, should we change the name of the container ?
Not sure if juniper/pyez-ansible is the most appropriate name
I would suggest something like juniper/ansible-galaxy

@ntwrkguru, @vnitinv Thoughts ?

[ntwrkguru]

How about just juniper/ansible-junos?