makefile: remove unused or outdated targets

Makefile

@@ -13,21 +13,5 @@ build:
 	docker build -t $(NAME):$(VERSION) .
 	docker save $(NAME):$(VERSION) | gzip -9 > build/$(NAME)_$(VERSION).tgz
 
-release:
-	rm -rf release && mkdir release
-	go get github.com/progrium/gh-release/...
-	cp build/* release
-	gh-release create gliderlabs/$(NAME) $(VERSION) \
-		$(shell git rev-parse --abbrev-ref HEAD) $(VERSION)
 
-docs:
-	boot2docker ssh "sync; sudo sh -c 'echo 3 > /proc/sys/vm/drop_caches'" || true
-	docker run --rm -it -p 8000:8000 -v $(PWD):/work gliderlabs/pagebuilder mkdocs serve
-
-circleci:
-	rm ~/.gitconfig
-ifneq ($(CIRCLE_BRANCH), release)
-	echo build-$$CIRCLE_BUILD_NUM > VERSION
-endif
-
-.PHONY: build release docs
+.PHONY: build dev