FileIO integration

[s-celles]

Similar to s-celles/GPX.jl#4
FileIO integration might be considered here also
Pinging @alhirzel

[alhirzel]

PR #7

[s-celles]

I'm wondering if this is, in fact, a good idea for KMLTracks... because KMLTracks only handle tracks in kml files... so not any kind of kml files and associates attributes.

Anyway I think it's better to tackle GPX.jl integration with FileIO and have a look at KMLTracks later (if that's really a good idea)