Merge commit 'origin/next' into branch-2.1

Merge commit 'origin/next' into branch-2.1

* commit 'origin/next': (28 commits)
  Fix a typo in InitCluster
  Ignore results from drained nodes in iallocator
  Ship the ethers hook
  Ethers hook, compatibility with old lockfile
  Remove a few unused imports from noded/masterd
  Move HVM's device_model to a hypervisor parameter
  Implement the KERNEL_PATH parameter for xen-hvm
  Upgrade be/hv params with default values
  Add cluster-init --no-etc-hosts parameter
  objects: add configuration upgrade system
  Update NEWS and version for 2.0.3 release
  example ethers hook: use lockfile-progs
  ethers hook lock: use logger not echo
  ethers hook: reduce the probability of data loss
  devel/upload: revert rsync -p
  export: add meaningful exit code
  Fix detecting of errors in export
  Implement gnt-cluster check-disk-sizes
  rpc: add rpc call for getting disk size
  bdev: Add function for reading actual disk size
  ...

Conflicts:
	daemons/ganeti-masterd   - trivial, kept 2.1 version
	lib/bootstrap.py         - trivial, kept 2.1 version
	lib/cmdlib.py            - integrated the 2.0.3 changes
	lib/constants.py         - trivial
	lib/hypervisor/hv_xen.py - trivial, kept 2.1 version
	lib/objects.py           - trivial, kept 2.1 version
	lib/opcodes.py           - integrated the 2.0.3 changes

Signed-off-by: Iustin Pop <iustin@google.com>