Added python3 testapp build to Travis matrix

.travis.yml

@@ -19,6 +19,7 @@ env:
     - ANDROID_NDK_HOME=/opt/android/android-ndk
     - CRYSTAX_NDK_HOME=/opt/android/crystax-ndk
   matrix:
+    - COMMAND='. venv/bin/activate && cd testapps/ && python setup_testapp_python3.py apk --sdk-dir $ANDROID_SDK_HOME --ndk-dir $ANDROID_NDK_HOME --requirements sdl2,pyjnius,kivy,python3'
     # overrides requirements to skip `peewee` pure python module, see:
     # https://github.com/kivy/python-for-android/issues/1263#issuecomment-390421054
     - COMMAND='. venv/bin/activate && cd testapps/ && python setup_testapp_python2_sqlite_openssl.py apk --sdk-dir $ANDROID_SDK_HOME --ndk-dir $ANDROID_NDK_HOME --requirements sdl2,pyjnius,kivy,python2,openssl,requests,sqlite3,setuptools'

Dockerfile

@@ -44,7 +44,7 @@ RUN apt update -qq && apt install -qq --yes --no-install-recommends \
 RUN dpkg --add-architecture i386 && apt update -qq && apt install -qq --yes --no-install-recommends \
     build-essential ccache git libncurses5:i386 libstdc++6:i386 libgtk2.0-0:i386 \
     libpangox-1.0-0:i386 libpangoxft-1.0-0:i386 libidn11:i386 python2.7 python2.7-dev \
-    openjdk-8-jdk unzip zlib1g-dev zlib1g:i386
+    openjdk-8-jdk zip unzip zlib1g-dev zlib1g:i386
 
 # specific recipes dependencies (e.g. libffi requires autoreconf binary)
 RUN apt install -qq --yes --no-install-recommends \
@@ -93,7 +93,7 @@ RUN useradd --create-home --shell /bin/bash ${USER}
 # with sudo access and no password
 RUN usermod -append --groups sudo ${USER}
 RUN echo "%sudo ALL=(ALL) NOPASSWD: ALL" >> /etc/sudoers
-RUN pip install --quiet --upgrade Cython==0.28.6
+RUN pip install --quiet --upgrade cython==0.28.6
 WORKDIR ${WORK_DIR}
 COPY . ${WORK_DIR}
 # user needs ownership/write access to these directories