[BUG] Sequence values for id do not update if new entries manually added

[alexanderleegs]

Currently, our implementation for new entries to the table automatically increments the stored sequence value of the id by 1. However, this causes an issue whenever we make manual additions to the db - i.e. adding a new Site manually with id 1 more than the current max will cause the next time a Site is added to have the same id, which causes a conflict.

We should look into automatically checking for the current max id before inserting new entries into our db tables, otherwise we will need to execute setval every time we make manual additions to our db.