Add .editorconfig file to override IDE defaults

Add rules for enforcing tabs in Java, and spaces in Ruby.

Add a rule to make sure trailing whitespace is trimmed
and that no new final newline is inserted.

.editorconfig

@@ -0,0 +1,13 @@
+root = true
+
+[*]
+trim_trailing_whitespace = true
+insert_final_newline = false
+
+[*.java]
+indent_style=tab
+tab_width=4
+
+[*.rb]
+indent_style=space
+indent_size=2