Fix travis-ci builds (#842)

* Update .travis.yml - try explicit emulator vars

Line 8 comment:
    system-images;android-25;android-tv;x86
    system-images;android-25;android-wear-cn;armeabi-v7a
    system-images;android-25;android-wear-cn;x86
    system-images;android-25;android-wear;armeabi-v7a
    system-images;android-25;android-wear;x86
    system-images;android-25;google_apis;arm64-v8a
    system-images;android-25;google_apis;armeabi-v7a
    system-images;android-25;google_apis;x86
    system-images;android-25;google_apis;x86_64
    system-images;android-25;google_apis_playstore;x86
    system-images;android-26;android-tv;x86
    system-images;android-26;android-wear-cn;x86
    system-images;android-26;android-wear;x86
    system-images;android-26;google_apis;x86
    system-images;android-26;google_apis;x86_64
    system-images;android-26;google_apis_playstore;x86
    system-images;android-27;android-tv;x86
    system-images;android-27;google_apis;x86
    system-images;android-27;google_apis_playstore;x86

* Use android create --package option

EMULATOR environment variable

* Emulator subprocess to attempt QT fix

Recursive file listing for debug info

* fix emulator, add gradle setup