flight.js: Handle null elevations in getFixData()
tracking: Show elevation in barogram
model/auth: Added initials() method
templates/tracking: Display pilot initials as callsign
Merge pull request #27 from Turbo87/tracking-callsigns

Use user name initials for tracking callsigns
Merge branch 'master' into elevation

Conflicts:
	skylines/templates/tracking/view.jinja
tracking: Added elevation data to full screen page too
Merge pull request #28 from Turbo87/elevation

Display elevation in tracking barograms