Update dual boot tool

- Create 2GB dynamic growth sparse image
- Ext4 formatting fix
- Free space calculation fix

Change-Id: Ibdbc7499606e03e4981addf00c6735b450698afc
Use a common /cache partition for both recovery

This device HIDDEN partition too small for /cache partition

Change-Id: I5e2004bf4e5d9e2712136dbf5536a29119a50059
Centralized dual boot environment setup

Change-Id: I9729bfabf696e08fa9d9a8a7ac0a9b659a84a757