add elevation to exif tag as well, unless it doesn't exist in the GPX
Add a script to interpolate direction based on GPS EXIF tags
Merge pull request #18 from mprins/interpolate_image_direction

Add a script to interpolate direction based on GPS EXIF tags prior to upload
Merge pull request #19 from mprins/altitude_to_exif

add elevation to EXIF tag as well, unless it doesn't exist in the GPX