cycle between util and docs packages

there is some cycling between docs and util:

DateTimeHelper and ApplicationFactory from util depend on the docs package. For ApplicationFactory merely the get/setDocumentStore need to be moved, i.e. to a docs.DocumentStoreFactory class.

DateTimeHelper is heavily used in several docs classes and also in util.Logger. It would be nice to have the DateTimeHelper in docs. But Logger only uses the ONE_MINUTE and ONE_SECOND constants from DateTimeHelper. Thus, things could be easily resolved.