Refactor css

[greyhillman]

Fixes #6

Technically, this isn't a refactor as we're also changing the look of things.

Visual updates:

• made the buttons, inputs, and fieldsets have depth to them
  • the "Add place to rent" button now looks like it comes out of the page. When clicked, it becomes depressed.
  • the inputs are also raised above the page, except for disabled ones
  • the fieldsets have a shadow as if they're floating above the containing element
• removed the "edge" from the footer: replaced with links to my blog/portfolio site and GitHub for this project