Locale option is limited to only English(en) and Spainish (es)

[kidozh]

As illustrated in the title, it seems that timeago can only recognize en and es. It may due to the following lines which limit the language code.

https://github.com/andresaraujo/timeago.dart/blob/8ad8d267641c30b2d20d9fe25756880e04d0e5bb/timeago/lib/src/timeago.dart#L7-L12

In this case, only en, en_short, es and es_short can be registered.

PS, the language code in Chinese would have problems since the language code zh should be pointed at simplified Chinese.