updated Docker Client to accept TLS
removed hard-coded `http` in Docker client
cleanup docker.New to overload, so to speak
minor docker client refactoring
pass docker cert and key as byte arrays or file paths
drone client accepts docker host, cert and key
Fix incorrect drone branch for pull requests

Fixes #607
updated README
Merge pull request #599 from bradrydzewski/remote-workers

Updated Docker Client to accept TLS
Merge pull request #608 from shopa/fix-wrong-drone-branch

Fix incorrect drone branch for pull requests
Add docker section in .drone.yml with net option
Merge pull request #617 from floatdrop/docker-section-in-yaml

Add docker section in .drone.yml with net option
fixe #620
Merge pull request #622 from bradrydzewski/master

fixes #620
Merge branch 'master' of https://github.com/drone/drone into private-repo

Conflicts:
	shared/build/docker/client.go