Introduced ModuleManager and copied code with as little changes as possible into ModuleManager.

Signed-off-by: jdo <juergen.donnerstag@gmail.com>
applied patch with BlockingAction update
Created DownloadHttpClient out of boilerplate in DefaultModuleRepository
and changed DefaultModuleRepository accordingly.
Changed URL to URI around VericleManager and friends
Changed the ModuleRepository API slightly to ease respository management by ModuleManager.
Introduced LocalModuleRepository as an alternative; also useful for testing
Started with ModuleManagerTest to more easily test features such as preserve-cwd
documentation and other cleanup
Introduced a little ModuleWalker
Introduced VertxModule to provide easy access to a module config, but also its files. It's also nice for testing, as its now possible to simulate modules.
change the ModuleWalker API slightly and tested simulating modules