Fix if 'data' variable is a bytes-like object (decode utf-8 string)

When running ```./texturecache c``` i got this error:

```python
Traceback (most recent call last):                
  File "./texturecache.py", line 7168, in <module>
    main(sys.argv[1:])
  File "./texturecache.py", line 7011, in main
    extraFields=_extraFields, query=_query)
  File "./texturecache.py", line 3708, in jsonQuery
    lastRun=lastRun, secondaryFields=secondaryFields, uniquecast=UCAST)
  File "./texturecache.py", line 2583, in getData
    self.getDataProxy(mediatype, REQUEST, trim_cast_thumbs=(action != "dump"), uniquecast=uniquecast))
  File "./texturecache.py", line 2596, in getDataProxy
    data = self.chunkedLoad(mediatype, request, trim_cast_thumbs, idname=idname, silent=silent, uniquecast=uniquecast)
  File "./texturecache.py", line 2635, in chunkedLoad
    data = self.sendJSON(request, idname)
  File "./texturecache.py", line 1708, in sendJSON
    for m in self.parseResponse(udata):
  File "./texturecache.py", line 1798, in parseResponse
    idx = _w(data, 0).end()
TypeError: can't use a string pattern on a bytes-like object
```
This commit is fixing the issue.