Description of problem:
When user provide directory to ipa-restore command, command should check
availability of backup archive file before proceeding.

[root@server1 ~]# ipa-restore /tmp/
Directory Manager (existing master) password:

Preparing restore from /tmp/ on server1.testrelm.test
Cannot read backup metadata: [Errno 2] No such file or directory: '/tmp/header'
The ipa-restore command failed. See /var/log/iparestore.log for more
information

Version-Release number of selected component (if applicable):
# rpm -qa ipa-server 389-ds-base selinux-policy
389-ds-base-1.3.6.1-5.el7.x86_64
selinux-policy-3.13.1-141.el7.noarch
ipa-server-4.5.0-6.el7.x86_64

How reproducible:
100%

Steps to Reproduce:
1. Install ipa-server on fresh machine
2. Without ipa-backup, run ipa-restore on given directory

Actual results:
Command fails with above error.

Expected results:
Command should notify user about non-availability of archival file in given
location.