Update wunderground.coffee

Improvement based on comment in pull request #1294 by https://github.com/technicalpickles

Author: bestimmaa

src/scripts/wunderground.coffee

@@ -88,10 +88,8 @@ get_data = (robot, msg, location, service, query, cb, lifetime, stack=0) ->
 
 send_forecast = (msg, location, data) ->
   report = data.forecast.txt_forecast.forecastday[0]
-  if not process.env.HUBOT_WUNDERGROUND_USE_METRIC?
-    msg.send "#{report.title} in #{location}: #{report.fcttext} (#{formatted_ttl data})"
-  else
-    msg.send "#{report.title} in #{location}: #{report.fcttext_metric} (#{formatted_ttl data})"
+  useMetric = process.env.HUBOT_WUNDERGROUND_USE_METRIC?
+  msg.send "#{report.title} in #{location}: #{if useMetric then report.fcttext_metric else report.fcttext} (#{formatted_ttl data})"
 send_radar = (msg, location, data) ->
   msg.send "#{data.radar.image_url}#.png"