setup and rubocop corrections

.editorconfig

@@ -0,0 +1,17 @@
+# http://editorconfig.org
+
+root = true
+
+[*]
+indent_style = space
+indent_size = 2
+end_of_line = lf
+charset = utf-8
+trim_trailing_whitespace = true
+insert_final_newline = true
+
+# Trailing whitespace is significant in markdown files.
+[*.md]
+indent_size = 4
+trim_trailing_whitespace = false
+