Remove description method from SpaceBeforeBrace

The `description` method is being deprecated.

While here, also changed from appending to the `@lints` instance
variable directly to using the `add_lint` helper.

Change-Id: If2902858e2cd29c06759294c4d6357690aec6017
Reviewed-on: http://gerrit.causes.com/36725
Tested-by: jenkins <jenkins@causes.com>
Reviewed-by: Shane da Silva <shane@causes.com>