This patch deprecates the type argument of the review_request_closed

and review_request_closing signals, due to shadowing the type

builtin. We still provide the type argument, but it is wrapped in a

lazy object that will emit a warning when casted to a unicode string. We

now include the close_type argument which takes the place of the old

type argument. Usages and unit tests have been updated for this new

behaviour.

Ran unit tests.