Functions including pre backup/restore checks, take a snapshot of the
vault, and restore a snapshot from tarball. These functions will
support ansible-playbook for backup and restore of the vault.
Test Plan:
PASS bashate
PASS unit test
PASS snapshot and snapshot restore procedure, as presented in
ansible-playbooks I324b270ec738f864410068c4ac661301ca8176fd
Change-Id: Id786105aa8ddba2e77085b3897c0c8efd7e98c9b
Signed-off-by: Michel Thebeau <Michel.Thebeau@windriver.com>