Start fetshing vaadin versions by new way
Change directory for vaadin-clients from ".../tomcat-{version}/webapps/ROOT/WEB-INF/lib/vaadin-clients-jars/" to ".../tomcat-{version}/webapps/ROOT/WEB-INF/vaadin-clients-jars/"
refactor fetching releases
VAADINPNL-16  Change fetching vaadin-version list
 Refactor fetching releases