fixed one bug, added CSS hooks, changed contract show page to left heading table

Changes below look worse than they are (mostly due to changes in indenting I think)

1. There was one `can_by_edited_by?(@user)` leftover from an old version of the code.
2. I wrapped each page's content in a div for better CSS targeting.
3. I switched the contract show page to use a table to make it cleaner looking.