Problem: Android CI build need a way to disable GRADLE automatic tests.
Problem: Android CI build need a way to disable GRADLE automatic tests.

Reasons:

- ZYRE tests fail if the host firewall blocks ZRE or any other required port.

- ZYRE tests may fail if 2 or more tests are launched in parallel (SHOUT messages are received by the wrong test client).

Solution: Provide a variable to pass specific options to GRADLEW.

How to use:

    export ZYRE_GRADLEW_OPTS="-x test"
    cd zyre/bindings/jni
    ./ci_build.sh

ZYRE CI build scripts also build CZMQ, with a different call to GRADLEW.
To pass options to CZMQ GRADLEW, use the following:

    export CZMQ_GRADLEW_OPTS="xxx"
    cd zyre/bindings/jni
    ./ci_build.sh

If one wants to disable ZYRE & CZMQ gradlew automatic tests, use
the following:

    export CZMQ_GRADLEW_OPTS="-x test"
    export ZYRE_GRADLEW_OPTS="-x test"
    cd zyre/bindings/jni
    ./ci_build.sh

Note: This adds another possibility to build ZYRE JNI releases.
Old way was like :

    export TRAVIS_TAG="yes"
    cd zyre/bindings/jni
    ./ci_build.sh

New way can be (with or without '-x test'):

    export ZYRE_GRADLEW_OPTS="-PisRelease"
    cd zyre/bindings/jni
    ./ci_build.sh

zeromq/zproject,zeromq/zproject,zeromq/zproject