v1.9

Version 1.9

• Update README
• Make --compress option configurable, it is now possible to set
  compression level (--compress=X) (#77)
• Fix offline backup of virtual machines with multiple disks attached: nbd
  connection would use wrong socket file. (#76)
• Fix offline backup of remote vms: set missing socket file parameter.

Full Changelog: v1.8.2...v1.9