Factor out global env vars in .travis.yml
Factor out global env vars in .travis.yml

This should make it slightly more obvious which job is which when
looking at Travis build results.

Growstuff/growstuff,yez/growstuff,cesy/growstuff,yez/growstuff,Growstuff/growstuff,cesy/growstuff,Br3nda/growstuff,dv2/growstuff,pozorvlak/growstuff,pozorvlak/growstuff,Br3nda/growstuff,dv2/growstuff,cesy/growstuff,Growstuff/growstuff,dv2/growstuff,dv2/growstuff,Br3nda/growstuff,yez/growstuff,Growstuff/growstuff,yez/growstuff,pozorvlak/growstuff,Br3nda/growstuff,cesy/growstuff,pozorvlak/growstuff