Can't add RSS Feed - database seems to be wrong.

[Jonathan Gille]

When I try to add an external source, like an RSS feed, I get the following error.

Traceback (most recent call last):
  File "/home/user/streetsign-server/.virtualenv/lib/python2.7/site-packages/flask/app.py", line 1997, in __call__
    return self.wsgi_app(environ, start_response)
  File "/home/user/streetsign-server/.virtualenv/lib/python2.7/site-packages/flask/app.py", line 1985, in wsgi_app
    response = self.handle_exception(e)
  File "/home/user/streetsign-server/.virtualenv/lib/python2.7/site-packages/flask/app.py", line 1540, in handle_exception
    reraise(exc_type, exc_value, tb)
  File "/home/user/streetsign-server/.virtualenv/lib/python2.7/site-packages/flask/app.py", line 1982, in wsgi_app
    response = self.full_dispatch_request()
  File "/home/user/streetsign-server/.virtualenv/lib/python2.7/site-packages/flask/app.py", line 1614, in full_dispatch_request
    rv = self.handle_user_exception(e)
  File "/home/user/streetsign-server/.virtualenv/lib/python2.7/site-packages/flask/app.py", line 1517, in handle_user_exception
    reraise(exc_type, exc_value, tb)
  File "/home/user/streetsign-server/.virtualenv/lib/python2.7/site-packages/flask/app.py", line 1612, in full_dispatch_request
    rv = self.dispatch_request()
  File "/home/user/streetsign-server/.virtualenv/lib/python2.7/site-packages/flask/app.py", line 1598, in dispatch_request
    return self.view_functions[rule.endpoint](**req.view_args)
  File "/home/user/streetsign-server/streetsign_server/views/feeds_and_posts.py", line 490, in external_data_source_edit
    source.feed = Feed.get() # set initial feed
  File "/home/user/streetsign-server/.virtualenv/lib/python2.7/site-packages/peewee.py", line 5064, in get
    return sq.get()
  File "/home/user/streetsign-server/.virtualenv/lib/python2.7/site-packages/peewee.py", line 5450, in get
    (clone.model, sql, params))
FeedDoesNotExist: <class 'streetsign_server.models.Feed'> instance matching query does not exist:
SQL: SELECT "t1"."id", "t1"."name", "t1"."post_types" FROM "feed" AS "t1" LIMIT 1 OFFSET 0
Params: []