More design:

Background, alignmenet of the form, images and some normalization
new file:   app/assets/images/arrow.png
new file:   app/assets/images/back-test3.jpg
new file:   app/assets/images/background.jpg
modified:   app/assets/stylesheets/application.css
modified:   app/assets/stylesheets/main.scss
modified:   app/assets/stylesheets/nav.scss
modified:   app/assets/stylesheets/search.scss
modified:   app/assets/stylesheets/variables.scss
modified:   app/views/activities/_search_form.html.erb
modified:   app/views/activities/_when_search.html.erb
Merge branch 'design'