Add .editorconfig

Signed-off-by: Joe Grund <jgrund@whamcloud.io>

.editorconfig

+# http://editorconfig.org
+root = true
+
+[*]
+indent_style = space
+end_of_line = lf
+charset = utf-8
+trim_trailing_whitespace = true
+insert_final_newline = true
+max_line_length = off