Rails.logger should have level specified by config.log_level. 

Fix bug when log level of Rails.logger (which was set via config.logger) does not match the config.log_level.

Example:
```
# in config/application.rb
 config.logger = Logger.new(STDOUT)

# in config/environments/development.rb
 config.log_level = :info
```

Start rails console for example
```
$ rails c
> Rails.logger.level
=> 0
> ActiveSupport::Logger::INFO == Rails.logger.level
=> false 
```