Configuration properties must be defined and accessed using lower-cas…

…e kebab format jmix-framework/jmix#239

Configuration properties names changed to kebab case in all *.properties files;
Configuration properties names changed to kebab case everywhere property value is accessed from the code;
application.properties in new project templates now use kebab case property names;

datatools-ui/src/main/resources/io/jmix/datatoolsui/module.properties

@@ -13,5 +13,5 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 #
-jmix.ui.menuConfig = io/jmix/datatoolsui/menu.xml
+jmix.ui.menu-config = io/jmix/datatoolsui/menu.xml