tracking/list: Show altitude GND if available
Merge remote-tracking branch 'tbl/master'
assets: Added SimpleClosureJS filter

This will allow an AdvancedClosureJS filter later on
assets: Disable IE checks only for the flot bundle
Merge pull request #25 from Turbo87/closure

Added custom ClosureJS filter
tracking/list: Rename GND to AGL

As AGL means above ground level whereas GND stands for ground