Accounting for Strava's 0/0 lat/lng pts and missing altitudes, Endomondo's missing distances. Updated sanity check, gpxio, waypoint tostring method, and everything else to allow for null altitudes, latitudes, longitudes. Added more pre-checks for stationary strava activities. Removed unneeded dropbox cacheing of activity distance.
Some typos from the last commit, put exceptions into the main log in addition to the db.