Fix AVD test (#67)

* chcwd in docker

* Update Dockerfile

* Update Dockerfile

Author: gengjiawen

Dockerfile

@@ -86,4 +86,5 @@ RUN curl -sS https://dl.google.com/android/repository/${SDK_VERSION} -o /tmp/sdk
         "build-tools;$ANDROID_TOOLS_VERSION" \
         "add-ons;addon-google_apis-google-23" \
         "system-images;android-19;google_apis;armeabi-v7a" \
-        "extras;android;m2repository"
+        "extras;android;m2repository" \
+    && rm -rf /opt/android/.android