Feature translation status country flags

The method `translations_status_flags` works similar to `translation_status`. But instead of showing a string representing each locale translated, a little flag is shown:

![flags](https://f.cloud.github.com/assets/14915/692393/889bca92-dc22-11e2-9a7e-d8027cf934f8.jpg)

The flag icons used come from (FamFamFam)[http://www.famfamfam.com/lab/icons/flags/]: "These flag icons are available for free use for any purpose with no requirement for attribution."

Some work/cleanup is still required, because the country flags represent countries - not languages. For instance, I had to copy the flag of Great Britain (`gb.gif`) to `en.gif`. However, this could be scripted, with a mapping between ISO-3166 Country Codes and ISO-639 Language Codes. (I could not quickly find such a mapping.)