Save track name into .gpx file

[Danfro]

Originally reported by @Talkless under ernesst#36

I use ActivityTracker to record GPX track and use them to map hiking paths into OpenStreetMap maps.

Here's screenshot from (probably most advanced) OpenStreetMap editor JOSM, showing information about selected .gpx track:

It shows that .gpx file could have name and description, but it has none.

GPX schema does show that file can have "name":
https://www.topografix.com/GPX/1/1/gpx.xsd

It would be useful to export names into .gpx file too, as names do already exist in ActivityTracker application. For example, I would write "Path" or "Track grade5" to mark what kind of object am I recording.