Multi does not detect renamed files in status

Currently, when you rename a file, ``multi status`` will show a deleted file and a new file instead of a renamed file.

To reproduce:

```
echo "test" > test.txt
multi commit -m "A commit"
mv test.txt test2.txt
multi status
```

Current output:
```
	deleted:  test.txt
	new file: test2.txt
```

Expected output:
```
	renamed: test.txt -> test2.txt
```
