remove Utility.Conditional and use IfElse

This drops the >>! and >>? with the nice low fixity. IfElse does have
undocumented >>=>>! and >>=>>? operators, but I deem that too fishy.
Anyway, using whenM and unlessM is easier; I sometimes mixed the operators
up.

Remote/Rsync.hs

@@ -181,8 +181,8 @@ withRsyncScratchDir a = do
 	liftIO $ createDirectoryIfMissing True tmp
 	nuke tmp `after` a tmp
 	where
-		nuke d = liftIO $ 
-			doesDirectoryExist d >>? removeDirectoryRecursive d
+		nuke d = liftIO $ whenM (doesDirectoryExist d) $
+			removeDirectoryRecursive d
 
 rsyncRemote :: RsyncOpts -> [CommandParam] -> Annex Bool
 rsyncRemote o params = do