Merge branch 'devel-2.1'

* devel-2.1:
  Add disk cache control parameter for KVM
  Change pyinotify import for broader compatibility
  ClusterMasterQuery: add primary ip field
  confd ClusterMasterQuery: allow fields request
  Simplify utils.ReadFile
  DRBD: ignore unreadable meta devices
  gnt-cluster verify: Warn if node time diverges too far
  KVM: fail when a routed nic has no ip
  Enable batch mode for devel/upload
  cmdlib: Work around race condition in DRBD before version 8.0.13