No need to export these environment variables.

These variables has different values in host and container.  Specify
their values in docker command.
glogon-server
Restore BACKUP_LAB_DIR only when LAB_DIR not existing.

If LAB_DIR exists, it means it's not the first time that this test
runs.  It's unnecessary to restore it again.
Change initial password.
Force mysql to use "genee" as user.
Change mysql link name from `db` to `mysql`.
Merge pull request #6 from dochang/next

Improvements