Improved MacOS Python build (apache#4039)

### Motivation

Fixed the Python wheels build on MacOS using vagrant.
 * Use images with pre-installed XCode and dependencies
 * Unified Py 2 and 3 in a single VM

.gitignore

@@ -60,10 +60,8 @@ deployment/terraform-ansible/aws/terraform.tfstate.backup
 **/.vagrant
 
 
-pulsar-client-cpp/python/pkg/osx/**/*.bak
-pulsar-client-cpp/python/pkg/osx/**/build.sh
-pulsar-client-cpp/python/pkg/osx/**/*.whl
-pulsar-client-cpp/python/pkg/osx/**/*.template2
+pulsar-client-cpp/python/pkg/osx/*/*.bak
+pulsar-client-cpp/python/pkg/osx/*/*.whl
 pulsar-client-cpp/python/wheelhouse
 
 # CI generated files

pulsar-client-cpp/python/pkg/osx/generate-all-wheel.sh

@@ -18,33 +18,33 @@
 # under the License.
 #
 
-
 set -e
 
-printf "== Generate python 2.7 osx packages ==\n"
-
-cd osx-10.11-python2.7
-sh generate-wheel-file.sh
-cd ..
-
-cd osx-10.12-python2.7
-sh generate-wheel-file.sh
-cd ..
-
-cd osx-10.13-python2.7
-sh generate-wheel-file.sh
-cd ..
-
-printf "== Generate python 3.6 osx packages ==\n"
-
-cd osx-10.11-python3.6
-sh generate-wheel-file.sh
-cd ..
-
-cd osx-10.12-python3.6
-sh generate-wheel-file.sh
-cd ..
-
-cd osx-10.13-python3.6
-sh generate-wheel-file.sh
-cd ..
+if [ "$#" -lt 1 ]; then
+    echo "Need to specify git tag as argument"
+    exit 1
+fi
+
+export GIT_TAG=$1
+export GIT_REPO=${2:-https://github.com/apache/pulsar.git}
+
+echo "GIT_TAG: '$GIT_TAG'"
+echo "GIT_REPO: '$GIT_REPO'"
+
+OSX_VERSIONS=(
+    osx-10.12
+    osx-10.13
+    osx-10.14
+)
+
+for osx in ${OSX_VERSIONS[@]}; do
+    echo ""
+    echo "------------- BUILDING PYTHON WHEELS FOR $osx ---------------------"
+
+    pushd $osx
+    rm -rf *.whl
+    vagrant up --provision
+    vagrant scp :/Users/vagrant/pulsar/pulsar-client-cpp/python/dist/*.whl .
+    vagrant halt -f
+    popd
+done