Fix numerical parameter type

Some numerical parameters were set as string, this patch fixes this.

These discrepancies have been found because of the improvements of beat.core schemas.

advanced/algorithms/username/cepstral/1.json

@@ -21,9 +21,9 @@
   ],
   "parameters": {
     "rate": {
-      "default": "16000.0",
+      "default": 16000.0,
       "type": "float64",
-      "description": "sampling rate" 
+      "description": "sampling rate"
     }
   }
 }