Verification of lvmlockd (LVM2's new distributed locking daemon)
- modern replacement for clvmd (cf. #26)
- sanlock-based and dlm-based locking
- socket communication, based on same library as lvmetad (cf. #27)
- verification: besides internal threading and access to data structures, interaction of multiple lvmlockd instances (probably needs implementing a 'fake' locking mechanism, other than existing sanlock+dlm; would be also useful in testing)