Add "ignore list" to use when determining location of ActiveRecord call

[mikeweaver]

We have monkey patched the Mysql2Adapter, which, as a result, causes all our ActiveRecord calls to appear to originate from the monkey patch code, rather than the actual caller. I'd like to be able to configure a list of files that would be treated as if they were part of ActiveRecord, not our app, so the location the query was issued from will be accurate.

I would be happy to implement this, I just need some pointers as to where.

[mikeweaver]

Actually, I think I found the location in app_notifications.rb. I will get you a PR with a configurable ignore files list in a bit.