Prefer to pass block when logging.

The Logger by default includes a guard which checks for the
logging level. By removing the custom logging guards, we can decouple
the logging guard from the logging action to be done.

This also follows the good practice listed on http://guides.rubyonrails.org/debugging_rails_applications.html#impact-of-logs-on-performance.
Merge pull request #16099 from tgxworld/pass_log_as_block

Prefer to pass block when logging.