Code: Categorize case studies

[turanlioglu]

Categorize case studies according to the due date and assignment date.

The Newly Opened category will show the case studies related to the release date. (earlier to later) The In-progress category will show the case studies related to the due date. (closer to the due date will be listed top) The Closed category will show the case studies related to the effort spent (the more comment or work have will be listed in top)

The main page of the space will only show the 3 case studies per category, but when it Is clicked to category name it will show the all.

[turanlioglu]

Published date and due date fields are added, the related commit: 8b471c2

[turanlioglu]

Category links are added, later with these links, all the related cases will be seen under the categories, the related commit: 52c9e27

[turanlioglu]

Date details are added into the html, the related commit: a0602b9