module_formatter.return_data: use UTF-8 encoding

The text parameter can contain non-ASCII characters, so we'll encode it
using UTF-8. For example the DOCUMENTATION of the bzr module has such
characters in the name of the author.
Merge pull request #2432 from ciupicri/devel-unicode

module_formatter.return_data: use UTF-8 encoding
fail when service cannot be found by chkconfig
Merge pull request #2439 from jochu/service-chkconfig-fail

fail when service cannot be found by chkconfig
Mention of ansible-doc and man pages for modules.
Merge pull request #2447 from dorfsmay/20130318-ansible-doc

Mention of ansible-doc and man pages for modules.
invalidate group cache so that a group added by the add_host module will be relfected in the groups variable in later plays.
Merge pull request #2457 from robparrott/add_host-inventory-group-fix

invalidate group cache when adding a new group