added caching & pull completion
Fix completion when specifying `-H` option.
Use awk to remove headers instead of sed.
Fix completion of `docker run` when using optional arguments.
Allow multiple use of `-e`, `-p` and `-dns` for `docker run`
Implement `help` completion.
Implement `images` subcommand
Allow to specify image names using repository:tag format.
Add `commit` subcommand.
Fix user completion for `run`
Add completion for `search` subcommand.
Add completion for `build` subcommand.
Fix `-d` completion for `run` subcommand
Merge branch 'vincentbernat-fix' into master

Conflicts:
	_docker