Let user close more than one loan at the same time.

When closing loans, if they are from the same client (and made on the same
branch), let the user close more than one together.

TODO: gui tests will be updated later
Change-Id: I84d8023afab40c1fad41d35523a5f62a16d8d41a
Merge "Let user close more than one loan at the same time." into 1.7