Use a comprehensive name for configs

Identifying a Girder server by its url is not great. It would be great to have the URL be a setting instead of the title section. Potentially, if the url is missing, it would use the section title

e.g.
```
[Data @ kitware]
url = https://data.kitware.com
api_root = api/v1
default_location = {'_id': '5b22b7198d777f2e6225658c', '_modelType': 'folder'}

[https://data.kitware.com]
api_root = api/v1
default_location = {'_id': '5b22b7198d777f2e6225658c', '_modelType': 'folder'}

[https://data.kitware.com]
url = https://data.kitware.com/a/longer/path
api_root = api/v1
default_location = {'_id': '5b22b7198d777f2e6225658c', '_modelType': 'folder'}
```

Also:
Support URLs with ending '/'

No files, tests, or entry points are named in the issue. Start by locating the configuration parsing and Girder URL handling, then compare the three example section formats and trailing-slash behavior; done means the URL setting, title fallback, longer paths, and ending '/' are handled consistently.

Written by the indexing model from the issue text.