Html and Css
Reorganized code, added code to simplify and created partial.
- Moved @boostrap import and css background code to custom.css.scss instead of application.css.scc
- Added new and changed background image.
- Created a .content-wrapper and put it into application.html.erb
- Made css styling for .content-wrapper. Center, height and width.
- Added a _nav partial for bootstrap navigation. Took out the code from index, about and contact.

+ The 'Active' state on bootstrap nav needs to be changed to a helper method.
nav_link helper method

Created a helper method that associates the navigation button 'active' state with current webpage.