Include contributed completions in ubuntu PPA

Docker-DCO-1.1-Signed-off-by: Paul Jimenez <pj@place.org> (github: pjz)
Update Version to not use string anymore

Docker-DCO-1.1-Signed-off-by: Guillaume J. Charmes <guillaume@charmes.net> (github: creack)
Add API version to `docker version`

Docker-DCO-1.1-Signed-off-by: Guillaume J. Charmes <guillaume@charmes.net> (github: creack)
<3

Docker-DCO-1.1-Signed-off-by: Victor Vieux <victor.vieux@docker.com> (github: vieux)
Merge pull request #4964 from creack/add_api_version

Add API version to `docker version`
Merge pull request #4961 from creack/update_version_pkg

Update Version to not use string anymore
Merge pull request #4853 from pjz/bash_completion

Include completion scripts in ubuntu/debian package