save/load a local settings.yml file

Three user stories this applies to:

• As a space member, when I navigate to my space, I want to see a 'settings' tab/icon so that I can change space-specific settings
• As a space member, when I navigate to my space settings tab, I want to set a threshold specifying how many seeders must be online to ensure our backups are in the 'green', so that I can configure by backup alerts
• As a space member, when I navigate to my space settings tab, I want to set a tolerance margin for last seeing seeders, so that I can adjust my own comfort settings for how regularly my backups need to be made

Replicator is the parent class of Space, so if we do this in replicator, space will inherit this behaviour, while it also means replicators could also make use of this functionality if we chose to include it.

Example location:

~/.cobox.dev/1/profiles/0/spaces/50527b707353396443b77db65307f0b7275c320fdd65905c8f9c1d27c16ee2bf/settings.yml

Storage path is available in this.storage.

Example yaml:

threshold: 4 # some number
tolerance: 432000000 # 5 days in ms

• Validate the YAML so people manually changing it to invalid values will throw an error. For example, both fields should be numbers.
• Make all settings available through replicator.attributes