Fix two bugs in updateWellControls().

The bugs were:
  - Not accounting for the different storage orders used for the
    state.qs variable and the WellState*::wellRates() field.
  - When switching to rate control, well rates for phases other
    than that to be controlled by were set to zero.
Merge pull request #137 from atgeirr/fix-wellcontrolupdate

Fix two bugs in updateWellControls().