fix of LOGFACILITY on NC by MattS

fixes EUCA-4961
Fixing couple problems in NC init script

- virtualization flag check for KVM was not functional
- virtualization flag was failing for Xen unnecessarily

Fixes EUCA-7970, EUCA-7989
Fixing and normalizing instance dir cleanup

Introduced blobstore_delete_nonblobs() that is now used on
both normal instance termination and on fsck-induced instance
directory cleanup routine.

Fixes EUCA-7353
Added timeout and two retries to blkid invocation

Fixes EUCA-8083
Merge branch 'dev/dmitrii/3.4.1' into maint/3.4/testing