small bug fixes

rowers/dataprep.py

@@ -642,7 +642,7 @@ def join_workouts(r, ids, title='Joined Workout',
 
     while len(files):
         row2 = rdata(files[0])
-        if row2 != 0:
+        if row2 != 0 and row2 is not None:
             row = row+row2
         files = files[1:]
 

rowers/rojabo_stuff.py

@@ -1,5 +1,6 @@
 from rowers.models import Rower, Workout, TombStone
 from rowers import utils
+from rowers.utils import NoTokenError
 import datetime
 from django.utils import timezone
 from datetime import timedelta