[FEATURE] AccountCommandController

This adds an AccountCommandController which is able
to display the Accounts and Roles of a system in a
generic way. An (Abstract-) Party implementation is
not needed for the commands to work.

Change-Id: I5179f2c0fdbf4f1495e9e1e4f69749521bbb0036
Merge pull request #11 from afoeder/Issue5AccountComdCtrl

[FEATURE] AccountCommandController