Make URL:s clickable inside the description

Belongs to #39 -  Uses rails_autolink. Makes URLs clickable and opens new web page. Email addresses open default email app.
 Changes to be committed:
'New Idea' to the Navigation Bar & redirect to Idea

Added New Idea button to the navbar and after creating a new idea user can see the created idea (redirect_to @idea).
Merge pull request #40 from satukark/development

Make URLs clickable inside the description

resolves #39