Add HA functionality to WebHdfsClient (#2230)
Add HA functionality to WebHdfsClient (#2230)

Since version 2.1.0, the hdfs package allows to specify multiple
namenodes (HA functionality), by passing an url containing multiple
namenodes separated by ';'. This functionality is forwarded through to
WebHdfsClient in this commit.
foursquare/luigi,PeteW/luigi,soxofaan/luigi,spotify/luigi,foursquare/luigi,Magnetic/luigi,edx/luigi,Magnetic/luigi,samuell/luigi,PeteW/luigi,foursquare/luigi,Houzz/luigi,jamesmcm/luigi,rayrrr/luigi,samuell/luigi,samuell/luigi,spotify/luigi,adaitche/luigi,Houzz/luigi,riga/luigi,jamesmcm/luigi,Magnetic/luigi,jamesmcm/luigi,dlstadther/luigi,riga/luigi,soxofaan/luigi,riga/luigi,Magnetic/luigi,PeteW/luigi,soxofaan/luigi,riga/luigi,rayrrr/luigi,soxofaan/luigi,edx/luigi,Houzz/luigi,edx/luigi,adaitche/luigi,foursquare/luigi,rayrrr/luigi,dlstadther/luigi,jamesmcm/luigi,PeteW/luigi,samuell/luigi,Houzz/luigi,adaitche/luigi,spotify/luigi,dlstadther/luigi,dlstadther/luigi,edx/luigi,spotify/luigi,adaitche/luigi,rayrrr/luigi