Uses editorconfig to maintain consistent coding styles

Removes the following as they unnecessary
/* -*- Mode: Java; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set shiftwidth=2 tabstop=2 autoindent cindent expandtab: */

.editorconfig

@@ -0,0 +1,17 @@
+root = true
+
+[*.{js,jsm,html,css}]
+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
+
+[COMMIT_EDITMSG]
+max_line_length = 0