update travis caching rules for android changes
update travis caching rules for android changes

We don't want files that get touched every time we run to cause us to upload a new cache every build.

Closes #1398
carls-app/carls,StoDevX/AAO-React-Native,carls-app/carls,StoDevX/AAO-React-Native,StoDevX/AAO-React-Native,carls-app/carls,carls-app/carls,StoDevX/AAO-React-Native,carls-app/carls,carls-app/carls,StoDevX/AAO-React-Native,StoDevX/AAO-React-Native,StoDevX/AAO-React-Native,StoDevX/AAO-React-Native,carls-app/carls,StoDevX/AAO-React-Native