link_tile returns a new uuid as a bytestring

[Chadius]

When you register a Higlass file via /api/v/link_tile, the uuid is a byte string instead of an encoded string. In Python 3, it turns the uuid into an encoded string "b'<tileset_info>'", including the b''

I send this payload

{
'coordSystem': 'GRCh38', 
'filepath': '<AWS Bucket>/<Filename>.chrom.sizes', 
'filetype': 'chromsizes-tsv', 
'datatype': 'chromsizes'
}

res = requests.post(
                higlass_server + '/api/v1/link_tile/',
                data=json.dumps(payload),
                auth=authentication,
                headers=headers
            )

The server returns {'uuid': "b'Cr1CSDnZSEqMW-Q2lM01Mw'"}

The uuid should be encoded to match the JSON response.