+ Adding some default empty list values where applicable
neighbors now has a default value of '[]' to enforce the "empty list" constraint on that field
This dep was already there but just being used (as we're using serde). Now we can use it at the db layer which makes neighbor struct creation easier
* Cargo locks are being updated to reflect new dependancy changes
These changes actually reduce the dependancy count overall
+ Adding a very simple table to hold all the neighbors that an instance may want to reference
At some point we may want to support vanity join urls and this would be a good place to reference those
There would also need to be a way for admins to add/edit/remove vanity urls but that's for another patch
