Break the fs package up into smaller parts.

The purpose of this is to make it easier to maintain and eventually to
allow the rclone backends to be re-used in other projects without
having to use the rclone configuration system.

The new code layout is documented in CONTRIBUTING.

cmd/sync/sync.go

@@ -2,7 +2,7 @@ package sync
 
 import (
 	"github.com/ncw/rclone/cmd"
-	"github.com/ncw/rclone/fs"
+	"github.com/ncw/rclone/fs/sync"
 	"github.com/spf13/cobra"
 )
 
@@ -37,7 +37,7 @@ go there.
 		cmd.CheckArgs(2, 2, command, args)
 		fsrc, fdst := cmd.NewFsSrcDst(args)
 		cmd.Run(true, true, command, func() error {
-			return fs.Sync(fdst, fsrc)
+			return sync.Sync(fdst, fsrc)
 		})
 	},
 }