Stop referencing removed attribute in Rails 5.1
Stop referencing removed attribute in Rails 5.1

This PR completely removes support for connection_id which was removed
from Rails 5.1.

https://github.com/rails/rails/commit/4565de0da14a4b3d75e8b1a652fcb6dcd947c451

This will probably break with older versions of Rails, so 1.1.1 will
probably be the last to support versions older than 5.1.

karnov/query_cache,karnov/query_cache