Simplified creating & updating a record

- Deleted TRANSACTION (It was completely pointless in this case)
- Used `db.lastInsertRowId` instead of executing another query...

+ I didn't make any benchmark ,but I quess that if somebody is updating/creating many records (models) this improvement will affected a speed (At least a little bit).

// Slightly off topic ,but is it good to have Sync adapter as it is? I mean, if I want to for example save ten models then the database connection is going to be opened and closed ten times, that's not good at all.
There's a small typo on the REPLACE INTO line, it should be `names.join(",")` not `columns.join(",")`. Will you fix that or would you prefer I do it? Other than that it passes all my tests and I'm okay with merging your PR.