Allow the Hazelcast plugin version to be overridden
Allow the Hazelcast plugin version to be overridden

The Java system property 'teamcity.build.cache.plugin.version' can be
set with the version of the plugin to use.
Resolves #2

rodm/teamcity-gradle-build-cache-plugin,rodm/teamcity-gradle-build-cache-plugin,rodm/teamcity-gradle-build-cache-plugin