Add support for previewing locally (#49)

Uses docker-compose to pull down pages-ready jekyll from Docker Hub.

Also lays down a Makefile with targets to lifecycle manage
docker-compose resources.

This lets you preview changes pre-commit so you dont commit 🚮!

Makefile

@@ -0,0 +1,37 @@
+.PHONY: all fire-up fire-down
+.SILENT: banner help
+
+SHELL := /bin/bash
+DOCKERCOMPOSE:= $(shell command -v docker-compose 2> /dev/null)
+
+default: help
+
+banner:
+	echo ""
+	echo "    _      _                  ___    _                    "
+	echo "   | |_   |_|   ___    ___   |  _|  |_|        ___    ___ "
+	echo "   |  _|  | |  |  _|  | -_|  |  _|  | |   _   |  _|  | -_|"
+	echo "   |_|    |_|  |_|    |___|  |_|    |_|  |_|  |_|    |___|"
+	echo ""
+
+help: banner
+	grep -E '^[a-zA-Z_-]+:.*?## .*$$' $(MAKEFILE_LIST) | sort | awk 'BEGIN {FS = ":.*?## "}; {printf "\033[36m%-30s\033[0m %s\n", $$1, $$2}'
+
+preflight:
+ifndef DOCKERCOMPOSE
+	$(error "docker-compose not found in PATH - is it installed?")
+endif
+
+fire-up: preflight ## Run docker-compose up -d
+	@docker-compose up -d && \
+		sleep 30 && \
+		open "http://0.0.0.0:4000/"
+
+fire-ps: preflight ## Run docker-compose down
+	@docker-compose ps
+
+fire-down: preflight ## Run docker-compose down
+	@docker-compose down
+
+fire-rm: preflight ## Run docker-compose rm
+	@docker-compose rm --force

docker-compose.yml

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+tirefire:
+  image: jekyll/jekyll:pages
+  command: bundle exec jekyll serve
+  ports:
+    - 4000:4000
+  volumes:
+    - .:/srv/jekyll