Allow non-ascii characters in sites.json (when enough astropy user base supports it)

[eteq]

#38 fixed an issue described in #36 where astropy doesn't correctly parse the sites.json file when it has non-ascii characters. While #38 fixes it, it does so by removing some characters that are proper names that really ought to be unicode. astropy/astropy#7082 fixes the underlying problem by making everything unicode-compliant in astropy. So this issue is about esentially reverting #38, and, more broadly, allowing UTF-8 in the site.json file.

We do not want to do this yet, however, as it will instantly break all released astropys (at the time of this writing). So instead, we are thinking to follow the suggestion of #36 (comment) - wait a while until we think most installed astropy have the fix (could be a long time...), and then bring in the non-ascii characters again.

[pllim]

Does this mean we can put emoji into observatory data?

[aarchiba]

JSON is capable of escaping non-ascii characters, and the python json module makes this easy. Would it solve the problems if this repository's contents contained only escaped Unicode? Or do old versions of astropy fail when the decoded data isn't Unicode?