feature/491: listing page for walkthroughs

* created a teaser view for walkthroughs
  * with edit link, if user has the permission
* themed the small widget for make it usable
fetaure/491: fixing problems reported by reviewer.

* use the l() function
* use the format_date() function
* check permission in preprocess.
feature/491: fixing problems reported by reviewer.
feature/491: fixing reported errors.
Merge pull request #73 from csanyiarpad/feature/491-walkthrough-listing-page-theming

feature/491: listing page for walkthroughs
Improves screening.

* better error handling
* variables named properly
* generates dummy screening node on walkthrough creation
Merge pull request #74 from tamasd/master

Improves screening.
Update Drupal core to 7.28
Hide the contents of CHANGELOG.txt
Add chosen module and library

https://drupal.org/project/chosen
Enable chosen module on site install and site update
Theme selectbox to match Walkhub style
Add og access module to dependencies and set subsribe permission to private roles.
Revert wt collactions feature and rebuild permission.
Merge branch 'master' into feature/collections
Merge pull request #75 from hosszukalman/feature/collections

Enable og access module ad rebuild node permissions
E_NOTICE fixes.
Merge branch 'master' of github.com:Pronovix/WalkHub
Removes unnecessary cases.
Merge pull request #76 from tamasd/master

E_NOTICE fixes.