Online passband history query not working

[aprsa]

phoebe.list_passband_online_history("Stromgren:u")
Traceback (most recent call last):
File "", line 1, in
File "/home/andrej/projects/phoebe/phoebe/phoebe/atmospheres/passbands.py", line 2206, in list_passband_online_history
return {k:v for k,v in all_history.items() if installed_timestamp < _timestamp_to_dt(k)} if installed_timestamp is not None else all_history
^^^^^^^^^^^^^^^^^
AttributeError: 'list' object has no attribute 'items'

[aprsa]

This PR fixes the history issue and supports ISO timestamps.

[aprsa]

The server is still not fully backwards-compatible, investigating.

[aprsa]

Fixed by this PR.