[PATCH] Fix for slightly different Strava export Format

Strava used other slightly other tags for it's gpx files.
Added those tags to the GpxParser.
Tested and verified.
As I don't have a Power Meter I can't verify Power is correctly imported.

Signed-off-by: Simon Egli <smn.egli@gmail.com>
Merge pull request #859 from Deadolus/Strava-fix

[PATCH] Fix for slightly different Strava export Format