Add search app who provides a basic config for haystack
Update CHANGELOG
Smart import for opps thirdy-apps who use haystack
Fix PEP8
Use python autoload for import OPPS_HAYSTACK_APPS modules
Update packages docs
Merge pull request #428 from opps/search_app

Search app using haystack
Merge branch 'stable/0.2.x' of github.com:opps/opps into issue_402

* 'stable/0.2.x' of github.com:opps/opps:
  Update packages docs
  Use python autoload for import OPPS_HAYSTACK_APPS modules
  Fix PEP8
  Smart import for opps thirdy-apps who use haystack
  Update CHANGELOG
  Add search app who provides a basic config for haystack
update Changelog