api.logout() doesn't provide "token" parameter

[GPHemsley]

Since the changes from #11 (which appear to have been necessary to fix another problem), I now get the following error when I call api.logout():

Traceback (most recent call last):
  File "/....py", line 46, in <module>
    api.logout()
  File "/.../src/ceterach/ceterach/api.py", line 299, in logout
    return len(self.call(action="logout", use_defaults=False)) == 0
  File "/.../src/ceterach/ceterach/api.py", line 272, in call
    return self._call(params, more_params, use_defaults=use_defaults)
  File "/.../src/ceterach/ceterach/api.py", line 217, in _call
    raise raiseme
ceterach.exceptions.CeterachError: 'missingparam': 'The "token" parameter must be set.'