add .editorconfig

.editorconfig

@@ -0,0 +1,18 @@
+root = true
+
+# Unix-style newlines with a newline ending every file
+[*]
+end_of_line = lf
+insert_final_newline = true
+indent_style = space
+indent_size = 4
+
+# Indentation override for all JS under lib directory
+[lib/**.js]
+indent_style = space
+indent_size = 2
+
+# Matches the exact files either package.json or .travis.yml
+[{package.json,.travis.yml}]
+indent_style = space
+indent_size = 2