specify require dependencies for python example (#14)
specify require dependencies for python example (#14)

the python example require websocket-client to be installed .
jai1/pulsar,sschepens/pulsar,ArvinDevel/incubator-pulsar,sschepens/pulsar,bradtm/pulsar,yahoo/pulsar,agarman/pulsar,saandrews/pulsar,jai1/pulsar,tkb77/pulsar,yush1ga/pulsar,tkb77/pulsar,bradtm/pulsar,tkb77/pulsar,merlimat/pulsar,nkurihar/pulsar,merlimat/pulsar,nkurihar/pulsar,yahoo/pulsar,ArvinDevel/incubator-pulsar,ArvinDevel/incubator-pulsar,tkb77/pulsar,sschepens/pulsar,yush1ga/pulsar,saandrews/pulsar,jai1/pulsar,massakam/pulsar,bradtm/pulsar,ArvinDevel/incubator-pulsar,ArvinDevel/incubator-pulsar,yahoo/pulsar,nkurihar/pulsar,ArvinDevel/incubator-pulsar,yush1ga/pulsar,nkurihar/pulsar,yush1ga/pulsar,bradtm/pulsar,sschepens/pulsar,ArvinDevel/incubator-pulsar,yush1ga/pulsar,bradtm/pulsar,nkurihar/pulsar,sschepens/pulsar,merlimat/pulsar,saandrews/pulsar,saandrews/pulsar,massakam/pulsar,jai1/pulsar,yahoo/pulsar,sschepens/pulsar,merlimat/pulsar,yahoo/pulsar,merlimat/pulsar,agarman/pulsar,saandrews/pulsar,saandrews/pulsar,jai1/pulsar,jai1/pulsar,tkb77/pulsar,saandrews/pulsar,yahoo/pulsar,yush1ga/pulsar,saandrews/pulsar,massakam/pulsar,tkb77/pulsar,ArvinDevel/incubator-pulsar,nkurihar/pulsar,yush1ga/pulsar,nkurihar/pulsar,jai1/pulsar,tkb77/pulsar,nkurihar/pulsar,tkb77/pulsar,massakam/pulsar,agarman/pulsar,jai1/pulsar,sschepens/pulsar,agarman/pulsar,massakam/pulsar,merlimat/pulsar,nkurihar/pulsar,sschepens/pulsar,massakam/pulsar,bradtm/pulsar,yush1ga/pulsar,jai1/pulsar