Lots of changes to layout and design, etc.

- Adjusting top bar logo to be centered vertically
- Adjusting top bar button padding
- Creating a second accent color for mixin scheme and refactoring color theme sass
- Adjusting top bar background color and opacity
- Hiding radio buttons on forms
- Adjusting top bar height to 64px
- Making listing thumbnail more squareish
- Declaring type class for centering (type.css.scss)
- Restyling form submit buttons
- New layout for top nav bar elements
- Added search placeholder on find spaces page
- Added note reminding to have Linkedin and Facbook URL storage for user profile