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/Multicast.hs

@@ -137,7 +137,7 @@ send ups fs = do
 				mk <- lookupFile f
 				case mk of
 					Nothing -> noop
-					Just k -> withObjectLoc k (addlist (fromRawFilePath f))
+					Just k -> withObjectLoc k (addlist f)
 			liftIO $ hClose h
 			
 			serverkey <- uftpKey