Add .editorconfig

.editorconfig

@@ -0,0 +1,15 @@
+# This file is for unifying the coding style for different editors and IDEs.
+# More information at http://EditorConfig.org
+
+# No .editorconfig files above the root directory
+root = true
+
+[*]
+indent_style = space
+indent_size = 4
+charset = utf-8
+trim_trailing_whitespace = true
+insert_final_newline = true
+
+[package.json]
+indent_size = 2