SMACK-53: create Version.Provider and .Manager

The Version.Provider is used to parse Version IQs. Integration:

	providerManager.addIQProvider("query", Version.NAMESPACE, new Version.Provider());

The Version.Manager is used to reply to Version IQs. Integration:

	Version.Manger.getInstanceFor(connection).setVersion(
		new Version("App Name", "1.23", "Operating System"));
SMACK-53: reviewer feedback updates

 * corrected extensions.provider
 * using weak connection reference in manager
 * license update
 * removed old namespace ELEMENT string
SMACK-53: remove flood protection
refactor Version.Manager and .Provider into own classes

This patch does:
 * refactor the Manager and Provider into separate classes in the
   hierarchy, comparable to iqprivate
 * update extensions.provider
 * rework how START_TAG parsing is done
 * re-use of the NAMESPACE element
 * removal of flood protection
 * weak-reference connection class
 * improve packet filter in the manager
 * add a test case