squash merge from dev branch

vendor/github.com/prometheus/client_model/ruby/Makefile

@@ -0,0 +1,17 @@
+VENDOR_BUNDLE = vendor/bundle
+
+build: $(VENDOR_BUNDLE)/.bundled
+	BEEFCAKE_NAMESPACE=Prometheus::Client protoc --beefcake_out lib/prometheus/client/model -I .. ../metrics.proto
+
+$(VENDOR_BUNDLE):
+	mkdir -p $@
+
+$(VENDOR_BUNDLE)/.bundled: $(VENDOR_BUNDLE) Gemfile
+	bundle install --quiet --path $<
+	@touch $@
+
+clean:
+	-rm -f lib/prometheus/client/model/metrics.pb.rb
+	-rm -rf $(VENDOR_BUNDLE)
+
+.PHONY: build clean