Not possible to take and restore host config snapshot using SnapshotBackup

[zebrik]

Currently SnapshotBackup is only able to take domain config snapstot not the host one.

[Ladicek]

This is ultimately the same thing as #160. Closing so that the discussion doesn't bifurcate.

[Ladicek]

Reopening after scope clarification: #160 is about a simple fix of backup/restore of domain.xml config, while this is about enabling backup/restore of host.xml config (which would require more work both in SnapshotBackup and ReloadToSnapshot).