Startup script: use wildcard for the classpath

This pattern improves the extensibility of the micro-service as extension JARs
can easily be added to lib/ folder and will be included at restart without the
requirement to modify the CLASSPATH in the executable

build.gradle

@@ -103,3 +103,7 @@ distributions {
 applicationDefaultJvmArgs = [
   "-Dvertx.logger-delegate-factory-class-name=io.vertx.core.logging.SLF4JLogDelegateFactory"
 ]
+
+startScripts {
+  classpath = files('$APP_HOME/lib/*')
+}