background color red if co2 emission is too high
share Track as JSON
fix for null pointer from previous commit
Merge branch 'master' of github.com:enviroCar/enviroCar-app

Conflicts:
	org.envirocar.app/res/values-de/strings.xml
	org.envirocar.app/res/values/strings.xml
show average co2 emission in track overview.
Merge branch 'master' of https://github.com/enviroCar/enviroCar-app