Added invoice page params.
Debug enabled (log msgs)
Added invoice fragment menu options.
Minor syntax changes.
Added basic invoice update menu and action structure.
Refactored actions.

Actions are based on the Command design pattern. We now add a BaseAction
class that takes care of context and user object initialization. It also
takes care of creating Vendor client instances by exposing a CRUD model
for the IClient based clients.
clientLogout now executed in the finally block
Fixed crash due to wrongly invoked client.close()
Added sample call from fragment to client stub.