unnecessary list() added during py3 port

instead of recursive bytes2unicode use a proper JSONEncoder to conver bytes->unicode for json.dumps()
removing excessive isinstance(data, bytes) checks
py3: / -> // and list() around .items() that gets modified in loop
moved lbrynet.undecorated to where its actually used and hopefully we can delete it eventually
removed build/upload_assets.py, travis can do all this now

lbrynet/blob/blob_file.py

@@ -149,7 +149,7 @@ class BlobFile:
     def writer_finished(self, writer, err=None):
         def fire_finished_deferred():
             self._verified = True
-            for p, (w, finished_deferred) in self.writers.items():
+            for p, (w, finished_deferred) in list(self.writers.items()):
                 if w == writer:
                     del self.writers[p]
                     finished_deferred.callback(self)