convert TopFilePath to use RawFilePath

Adds a dependency on filepath-bytestring, an as yet unreleased fork of
filepath that operates on RawFilePath.

Git.Repo also changed to use RawFilePath for the path to the repo.

This does eliminate some RawFilePath -> FilePath -> RawFilePath
conversions. And filepath-bytestring's </> is probably faster.
But I don't expect a major performance improvement from this.
This is mostly groundwork for making Annex.Location use RawFilePath,
which will allow for a conversion-free pipleline.

Command/Status.hs

@@ -61,6 +61,6 @@ displayStatus (Renamed _ _) = noop
 displayStatus s = do
 	let c = statusChar s
 	absf <- fromRepo $ fromTopFilePath (statusFile s)
-	f <- liftIO $ relPathCwdToFile absf
+	f <- liftIO $ relPathCwdToFile $ fromRawFilePath absf
 	unlessM (showFullJSON $ JSONChunk [("status", [c]), ("file", f)]) $
 		liftIO $ putStrLn $ [c] ++ " " ++ f