Merge remote branch 'devel-2.1'

* devel-2.1: (40 commits)
  Fix unused imports or add silences where needed
  bdev: Add a TODO and a pylint silence
  confd: add a TODO and a pylint disable
  pylint: Temporarily disable W0201
  Disable R0922 in pylint
  Further pylint disables, mostly for Unused args
  pylint: disable the similarities checker
  LUDiagnoseOS._DiagnoseByOS: remove unused arg
  daemons: handle arguments correctly and uniformly
  hv_xen/_GetConfigFileDiskData: remove unused arg
  jqueue/_CheckRpcResult: log the whole operation
  Optparse extenders have to obey a given API
  backend._OSOndiskAPIVersion: remove obsolete arg
  pylint cleanups: dangerous initializers
  Convert to static methods (where appropriate)
  Remove more unused variables
  Add targeted pylint disables
  burnin: move decorators out of classes
  Rename an ConfdInotifyEventHandler init argument
  Introduce a makefile lint rule
  ...

Conflicts:
	daemons/ganeti-confd  - removed imports
	daemons/ganeti-noded  - fixed new GenericMain