Create delete form

[ovidiuch]

• [x] Delete form class
• [x] Post delete form
• [x] Post image delete form
• [x] User delete form (put button back)
• [x] Self user delete form
• [x] Fix order of actions in users deletion (first confirm deletion, then collect entries and send them, then remove entries)

[ovidiuch]

Make some style changes along the way

• [x] Remove lines from tables, adjust paddings
• [x] Move entry controls to new column on the right, stripped of their text
• [x] Open Sans to admin entry headers
• [x] Update FontAwesome