ROOT & Xposed framework required!
Module Obb on SD attempts to make it seamless - just enable module, reboot and move obb's to SD card (to same folder: Android/obb) - that's that. No need to enter any path or whitelist/blacklist any app. Do you want to only move Obb from Grand Theft Auto? Then only move that obb. Obb on SD will detect "obb on SD" and enable hooks only for this single game.
Support: http://forum.xda-developers.com/xposed/modules/mod-obb-sd-v0-1-t2884004