add js8 decoding if available

owrx/feature.py

@@ -40,6 +40,7 @@ class FeatureDetector(object):
         "wsjt-x": ["wsjtx", "sox"],
         "packet": ["direwolf", "sox"],
         "pocsag": ["digiham", "sox"],
+        "js8call": ["js8", "sox"],
     }
 
     def feature_availability(self):
@@ -370,6 +371,12 @@ class FeatureDetector(object):
         """
         return reduce(and_, map(self.command_is_runnable, ["jt9", "wsprd"]), True)
 
+    def has_js8(self):
+        """
+        To decode JS8, you will need to install [JS8Call](http://js8call.com/)
+        """
+        return self.command_is_runnable("js8")
+
     def has_alsa(self):
         """
         Some SDR receivers are identifying themselves as a soundcard. In order to read their data, OpenWebRX relies