docker search

[joshbax189]

Adds docker-search-mode which lists output of docker search with transient commands to pull the image, or visit the Docker Hub url. (You can also specify a tag to pull, but the only way to find the tag is to visit the docker hub page; the docker-search cli function is pretty limited).

Each new search string used will create a fresh search buffer, but updating transient args only affects the current search buffer.

[Silex]

@joshbax189 would it make sense to try to rebase this on master?

[joshbax189]

Absolutely, should be easier with aio