subclassing VumiError, thanks @jerith
subclassing VumiError, thanks @jerith

harrissoerja/vumi,harrissoerja/vumi,TouK/vumi,vishwaprakashmishra/xmatrix,harrissoerja/vumi,vishwaprakashmishra/xmatrix,TouK/vumi,TouK/vumi,vishwaprakashmishra/xmatrix