install emulator on CI

.travis.yml

@@ -40,6 +40,10 @@ install:
   - yarn config set cache-folder $YARN_CACHE
   # android sdk
   - ./scripts/installAndroidSDK.sh
+  # android emulator
+  - echo yes | android update sdk --no-ui --all --filter "sys-img-armeabi-v7a-google_apis-25"
+  - echo no | android create avd --name AVD -t android-25 --abi google_apis/armeabi-v7a
+  - android list avd
   # fbsimctl
   - brew tap facebook/fb && brew install fbsimctl