Add .editorconfig file to allow editors/IDEs to auto apply the correct settings

.editorconfig

@@ -0,0 +1,21 @@
+# http://editorconfig.org/
+
+root = true
+
+[*]
+end_of_line = lf
+insert_final_newline = false
+charset = utf-8
+
+[*.{go,scss}]
+indent_style = tab
+
+[*.{js,jsx,json,html}]
+indent_style = space
+indent_size = 4
+
+[web/react/package.json]
+indent_size = 2
+
+[Makefile]
+indent_style = tab