Story: As a user of the Quay AiO, I want to be able to specify a custom mount point where Quay will store blobs, because for larger mirrors I need to be able to use separate volumes / storage devices than the root filesystem.

Acceptance criteria:

• the default moint point for Quay blobs is /mnt/quay/storage
• an option CLI switch exists to switch the above default
• the installer needs to account for SELinux labeling of the mount point, if applicable