Fix false positive remotes

Hardcoded `WP_CONTENT_DIR` and `WP_CONTENT_URL` does not reflect edge
case when `UPLOADS` and `UPLOADS_URL` constants are set.

If the 'UPLOADS' constant is defined, then it will override the
'upload_path' option and 'WP_CONTENT_DIR/uploads' path.

See: https://codex.wordpress.org/Function_Reference/wp_upload_dir
Merge pull request #144 from attitude/hotfix/upload_url_dir

Fix false positive remotes