Create improved Dockerfile with volume mounts for storing data

* Add volume mounts to Dockerfile to enable persisten storing of
  database and tokens when using docker
* Makefile helps with cleanup and building the Dockerfile
* Startup fires the predictify runtime inside the container
* `.dockerignore` contains files that are not needed by the docker,
  e.g. files that would otherwise slow build process down

Makefile

@@ -0,0 +1,19 @@
+.PHONY: all dockerfile clean
+
+TAG="unstable"
+PROJ_NAME="predictify"
+
+all: install dockerfile
+
+install:
+	mkdir -p ./data
+
+dockerfile: ./docker/Dockerfile
+	docker build \
+		--tag "$(PROJ_NAME):$(TAG)" \
+		--build-arg PROJ_NAME=$(PROJ_NAME) \
+		--file ./docker/Dockerfile \
+		.
+
+clean: ./spotify_scraped.db
+	rm -r ./data/spotify_scraped.db