Reduce libs needed for decrypt and clean up old decypt files

Trim cryptfs.c to remove functions that TWRP does not use for
decrypt and remove the need for libfs_mgr from cryptfs.c by
passing some items to cryptfs.c from the partition manager.

Add support for new fstab flags:
encryptable and forceencrypt=/path/to/cryptokey
For example:
flags=forceencrypt=/dev/block/platform/sdhci-tegra.3/by-name/MD1
Note that "footer" is the default, so you do not need to set this
flag on devices that use the footer for the crypto key.
Also add mounttodecrypt if you need to mount a partition during
the decrypt cycle for firmware of proprietary libs.

Clean up decrypt and only support one version

Android 5.0 lollipop decrypt should be backwards compatible with
older versions so we will only support one version, 1.3 that came
with 5.0 lollipop.

Remove support for Samsung TouchWiz decrypt. It does not work with
the latest versions of Samsung encryption anyway and it has not
been updated to work with any AOSP decryption higher than 1.1

Change-Id: I2d9c6e31df50268c91ee642c2fa090f901d9d5c9