Typo's in the multiple files

[venkatamahesh]

1.) https://github.com/openstack/rally/blob/master/rally/consts.py
         Line 20 : dirrect ==> direct

2.) https://github.com/openstack/rally/blob/master/rally/task/processing/utils.py
         Line 37 sample ==> simple
         Line 24 average ==> mean ( it might calculating average but the name should be mean itself
         Line 152 Ziper ==> Zipper

3.) https://github.com/openstack/rally/blob/master/rally/plugins/openstack/scenarios/sahara/node_group_templates.py
         Line 39 Haddop ==> Hadoop

4.) https://github.com/openstack/rally/blob/master/rally/plugins/openstack/scenarios/heat/stacks.py
         Line 36 Add ==> Create
         Line 67 Add ==> Create
         Line 118 Add ==> Create

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/218580

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/218580
Committed: https://git.openstack.org/cgit/openstack/rally/commit/?id=cdc844ff46decf5434be943ff77e7ec3cb5812d2
Submitter: Jenkins
Branch: master

commit cdc844ff46decf5434be943ff77e7ec3cb5812d2
Author: venkatamahesh <email address hidden>
Date: Sat Aug 29 21:09:20 2015 +0530

    Fixed some typos in the files

    dirrect => direct
    sample => simple
    and some typos in description of functions

    Change-Id: Id175ea43554f380e2b5b3f053178c44b70ac842c
    Closes-Bug: #1490141