Add support for the JPMS by declaring an Automatic-Module-Name

[Phil Smart]

Add an explicit Automatic-Module-Name to the MANIFEST.MF to avoid the maven-javadoc-plugin from putting spring webflow on the patch-module path when building Javadoc options (see MJAVADOC-652).

This also helps transition webflow to the module system - using a controlled name, rather than relying on automatic name derivation.