The test runner uses the prebuilt port forwarder apk from:
<source root>/other/test-runner/android/prebuilt directory.
You should rebuild and copy the apk to prebuilt directory if you are
making any changes to the source code or you are changing any project
properties.

To build the port forwarder service:

  - Make sure you have android SDK and latest 'ant' installed.
  - Set ANDROID_HOME environment variable to your android sdk root
    directory. For example:
    export ANDROID_HOME=/home/<username>/android-sdk/
  - Build port forwarder service using following ant command:

        ant debug

To update the apk used by test-runner:

    cp ./bin/org.khronos.portforwarder-debug.apk ../prebuilt/

Files build.xml, proguard-project.txt and project.properties are
autogenerated by 'android' tool and you normally don't need to
regenerate these files. In case you need to regenerate these files,
you can do it using android tool. Example command that regenerates
these files when run from project root dir:

    <android-sdk>/tools/android update project -p . --target android-19

Currently android-19 (KitKat) target is set for this service which
should run fine on android-L as well. If you want to change the
target, update the target field in project.properties file.
