move search action from project and user to a search controller

so that we have a global search.
However, the view is not still nice and the search box does not link to
this controller.
add a nicer view for the result search
make the search box in the header link to the search controller
add a new line after each user on the search results

there were no new lines, thus the list of users where appended one next
to the other
Merge pull request #52 from jordimassaguerpla/master

add search controller and view for the site