fix uniform in comoving volume prior file finding

tupak/gw/prior.py

@@ -4,6 +4,7 @@ from tupak.core.prior import *
 class UniformComovingVolume(FromFile):
 
     def __init__(self, minimum=None, maximum=None, name=None, latex_label=None):
+        self.__file__ = __file__
         FromFile.__init__(self, file_name='comoving.txt', minimum=minimum, maximum=maximum, name=name,
                           latex_label=latex_label)