Implement hashing for CSS filenames

Based on @ag_dubs work

Author: skade

.gitignore

@@ -1,9 +1,9 @@
 /target/
 **/*.rs.bk
 /node_modules
-/static/styles/app.css
-/static/styles/fonts.css
 /static/styles/*.map
 .sass-cache
 localhost*
-/static/styles/vendor.css
+/static/styles/vendor_*.css
+/static/styles/app_*.css
+/static/styles/fonts_*.css