Update rally-jobs files

*) Rename rally-scenarios that is quite misleading to rally-jobs.
   rally-jobs makes much more sense, cause it actually contains files
   related to rally job

*) Update rally-jobs/README.rst to add more info

*) Update rally-jobs/plugins/README.rst to expaling plugins

*) Add new directory rally-jobs/extra, this directory is copy pasted
   in gates and can be used for files that are required by some of
   benchmarks

Change-Id: I6d0c0435a4bb4658ddf4adb871bc36ab8c157f3e
Synced processutils and periodic_task modules

This is to avoid using gettextutils module in them to be able to drop
the module once we complete migration to oslo.i18n.

Included changes:

* openstack/common/_i18n.py:
  66bad01 Allow tempest to use new log w/o oslo.i18n

* openstack/common/log.py:
  ac4330d Make use_syslog=True log to syslog via /dev/log
  df774ff Import PublishErrorsHandler from oslo.messaging
  a3220c5 add list_opts to all modules with configuration options

* openstack/common/periodic_task.py:
  a3220c5 add list_opts to all modules with configuration options
  5d40e14 Remove code that moved to oslo.i18n

* openstack/common/processutils.py:
  5d40e14 Remove code that moved to oslo.i18n
  6ff6b4b Switch oslo-incubator to use oslo.utils and remove old modules
  6a60f84 Mask passwords in exceptions and error messages
  63c99a0 Mask passwords in exceptions and error messages
  e184dd3 Fix exception message in openstack.common.processutils.execute
  d6b55fb Remove `processutils` dependency on `log`
  33afb20 Fix broken formatting of processutils.execute log statement
  85f1784 Move nova.utils.cpu_count() to processutils module
  cdcc19c Mask passwords that are included in commands
  2a4d15d Merge "Allow passing environment variables to execute()"
  8a0f567 Remove str() from LOG.* and exceptions
  51778f9 Allow passing environment variables to execute()
  fcf517d Update oslo log messages with translation domains
  af41592 Catch OSError in processutils
  f773ea2 Fix i18n problem in processutils module

Change-Id: Ie2fe4b78af14a4fb7ce4fabed543877d4b0d48e6
Merge "Synced processutils and periodic_task modules"
Merge "Update rally-jobs files"