LVMv2: LVMv2 Support

-Although CM doesn't use TWRP, the twrp.fstab in the etc folder is
neccessary to the conversion process.

-This commit should consist of these commits:
1. https://github.com/Meticulus/slim_device_samsung_venturi/commit/7ccd47c874f9a00c0397c8e8f17f3faaf72e256b
2. https://github.com/Meticulus/slim_device_samsung_venturi/commit/6dd83396dcfa853119c840306fe8f10dbf142411
3. https://github.com/Meticulus/slim_device_samsung_venturi/commit/d7e52002e6d342b3bf45432327495ad6849401bc