If server fails it refuses to restart

[mitra42]

If I run the server with

python3 ./server.py --config_file sample_global_config.ini

and then ctrl-c out of it then a subsequent run fails until I do

rm -r /tmp/spatial_dict /tmp/contact_dict

with

`2020-05-03 19:00:03+1000 [-]   File "/Users/mitra/git/bct-server/contacts.py", line 73, in _load
2020-05-03 19:00:03+1000 [-]     self._load_key(code, blob)
2020-05-03 19:00:03+1000 [-]   File "/Users/mitra/git/bct-server/contacts.py", line 269, in _load_key
2020-05-03 19:00:03+1000 [-]     self.keys[key_tuple] = key_string
2020-05-03 19:00:03+1000 [-] AttributeError: 'SpatialDict' object has no attribute 'keys'

I'm not sure what is happening ...

[danaronson]

fixed in #101