Added first pass of HUC12 streamflow stats.
Cleaned up client to use map of param names to values instead of array of name/value objects.
Switching from Gage to Site terminology. 1st streamflow stats workflow step.
Switching from Gage to Site terminology. 2nd streamflow stats workflow step.
Switching from Gage to Site terminology. last streamflow stats workflow step.
Missed a spot or two.
Merge pull request #35 from cschroed-usgs/WATERSMART-271

Watersmart 271