FoveaBox support (#1339)

* add foveabox support

* format

* fix

* foveabox correct

* fix mean and std in config

* add foveabox in model zoo

* fix work_dir, typo, fovea_target and config issues

* add necessary comments

* fix yapf issue in C1 check

* fix yapf issue in C1 check

* rename configs

* update model urls and minor fix