let circleci dictate docker install

Makefile

@@ -86,6 +86,7 @@ docker: aufs
 	apt-get install -qq -y curl
 	egrep -i "^docker" /etc/group || groupadd docker
 	usermod -aG docker dokku
+ifndef CI
 	curl -sSL https://get.docker.com/gpg | apt-key add -
 	echo deb http://get.docker.io/ubuntu docker main > /etc/apt/sources.list.d/docker.list
 	apt-get update
@@ -95,6 +96,7 @@ else
 	apt-get install -qq -y lxc-docker
 endif
 	sleep 2 # give docker a moment i guess
+endif
 
 aufs:
 ifndef CI