Config parse refactoring and optimization

* On the fly old attribute names to new ones (before adding object in
  configuration).
* Separated standard items from templates to avoid unnecessary iterations, and
  reduce the dependency on is_tpl() method call.
* Fixed a limitation on services exclusion: when a service having dependencies
  was excluded, there were an error in dependencies handling. This is fixed by
  the explode phase refactoring.
* On the fly objects indexation during explode phase (no more call to
  create_reversed_list() is necessary) to optimize the explode phase.
* Added complex expression detection to use standard recursion for simple
  expressions (most of the situations) rather than complex tree parsing to
  optimize the explode phase.
* On the fly conflict detection and management (no more twins management nor
  call to remove_twins() is necessary).
* Adding and indexing items are now done through method calls for better
  control and easier update.
* On the fly service exclusion during explode phase.
* Hardened config check: declaring a service with no bound host nor hostgroup
  raise an error.
* Added arbiter and scheduler config dump under JSON notation on SIGUSR2.
Merge remote-tracking branch 'upstream/master' into config_parse_optimize

Conflicts:
	shinken/daemons/arbiterdaemon.py
	shinken/dispatcher.py
	shinken/objects/config.py
	shinken/objects/hostdependency.py
	shinken/objects/item.py
	shinken/objects/service.py
	shinken/objects/servicedependency.py
	test/etc/multi_hostgroups_def/test_specific.cfg
Reverted dispatcher.py logger change.
Enhanced item.py and service.py documentation.
Comments typos fix.
Fixed a bug regarding services_overrides parse.
Fixed logger calls.
Typo (renamed mamage_conflict in manage_conflict).
Made conflict warn message more informative.
Merge pull request #1311 from geektophe/config_parse_optimize

Enh : Config parsing rework (Part1). Explode part