Allow additional excluded paths for db backtrace

[zhuston]

Our project uses a custom database connection and it was always listed as the file source in the backtrace. Adding this feature allowed us to make use of the very helpful backtraces.

[joeyrush]

+1

This is useful when using packages that intercept queries (such as model caching). In my case I'm applying a vendor trait to my base model and so every query in my debugbar is showing a vendor path, which I really don't care about