Add .editorconfig (#361)

* add `.gitattributes`

This is to avoid having to deal with line endings on different OSes

Ref https://help.github.com/articles/dealing-with-line-endings/

* drop `.gitattributes` in favor of `.editorconfig`

.editorconfig

@@ -0,0 +1,15 @@
+# http://editorconfig.org
+root = true
+
+[*]
+charset = utf-8
+end_of_line = lf
+indent_size = 2
+indent_style = space
+insert_final_newline = true
+max_line_length = 80
+trim_trailing_whitespace = true
+
+[*.md]
+max_line_length = 0
+trim_trailing_whitespace = false