Support for local Docker builds

* add a git-ignored `local/` folder for Makefile/Dockerfile
* import `local/Makefile` to root Makefile
* add `.dockerignore`

.dockerignore

@@ -0,0 +1,18 @@
+.awcache
+.dockerignore
+.git
+.gitignore
+.github
+data*
+dist
+docker
+docs
+dump.rdb
+node_modules
+/local
+/tmp
+/vendor
+*.yml
+*.md
+/vendor
+/tmp