QA/TestCases/LUKS rescue mode (rootfs is encrypted)

Description
Support the use of encrypted filesystems for anything other than /boot using cryptsetup and LUKS. This includes install time creation/configuration, as well as integrated support in mkinitrd and initscripts (others?). Currently we are only pursuing support for encrypted devices using cryptsetup/LUKS.

When using encrypted file systems/block devices, the rescue mode functionality should continue to work as expected, and not create situations where the encryption leads to undesired errors; in particular, a user should be able to successfully enter rescue mode for a system that has its root fs on an encrypted block device.

References:
 * 1) Anaconda/Features/EncryptedBlockDevices
 * 2) Releases/FeatureEncryptedFilesystems

Steps To Reproduce
Set up the system that rescue mode will access: "Remove linux partitions on selected drives and create default layout" should create a partitioning scheme where the root filesystem in on an encrypted block device.
 * Boot anaconda
 * Proceed to the partitioning dialog
 * Select the checkbox item "Encrypt system"
 * Enter and confirm the passphrase in a pop up dialog for the encrypted filesystem
 * choose default partitioning layout and continue to the disk druid partition screen
 * continue with installation
 * after installation, restart the installer and select rescue mode
 * in rescue mode, verify the ability to successfully mount examine and change the contents of the root fs on the encrypted block device

Expected Results

 * Confirmed "Encrypt system" item is checked
 * Verify installation completes successfully
 * Upon restarting the installer in rescue mode, the user is asked for the LUKS passphrase
 * Confirm that rescue mode successfully mounted the root fs and that the user in rescue mode can make changes to the filesystem
 * Verify rescue mode session completes successfully