Add editorconfig.

.editorconfig

@@ -0,0 +1,20 @@
+# http://EditorConfig.org
+
+root = true
+
+
+[*]
+charset = utf-8
+indent_style = space
+indent_size = 4
+end_of_line = lf
+insert_final_newline = true
+trim_trailing_whitespace = true
+
+
+[{package.json,.travis.yml}]
+indent_size = 2
+
+
+[{*.md,*.jade}]
+trim_trailing_whitespace = false