[webservices] station URL builder

[Philip Crotwell]

HI

The "Channel" field in the station URL builder puts "cha" in the query
parameters, but from the docs it should be "chan". The result is that
if you use the query builder and specify "BHZ" you end up getting all
active channels at that station instead of just the one you wanted.

For example:
http://www.iris.edu/ws/station/query?net=II&sta=AAK&loc=00&cha=BH1&timewindow=1990-11-30%2C1990-11-30&level=resp

Philip