Add redirect generator to make Netlify's CDN redirect to the right places.

Netlify will redirect with a 301 status to the right places without the
need of a custom javascript file.

The current redirects.js is not removed so production can keep working
as it is for now.

Signed-off-by: David Calavera <david.calavera@gmail.com>

Makefile

@@ -1,4 +1,4 @@
-.PHONY: all build build-preview help serve
+.PHONY: all build build-preview generate-redirects help serve
 
 help: ## Show this help.
 	@awk 'BEGIN {FS = ":.*?## "} /^[a-zA-Z_-]+:.*?## / {sub("\\\\n",sprintf("\n%22c"," "), $$2);printf "\033[36m%-20s\033[0m %s\n", $$1, $$2}' $(MAKEFILE_LIST)
@@ -11,5 +11,8 @@ build: ## Build site with production settings and put deliverables in _site.
 build-preview: ## Build site with drafts and future posts enabled.
 	jekyll build --drafts --future
 
+generate-redirects: ## Generate a redirects file and copy it into the _site directory.
+	mkdir -p _site && REDIRECTS_PATH=_site/_redirects ruby redirects.rb
+
 serve: ## Boot the development server.
 	jekyll serve