Title modified using helpers

The title have been modified to use helpers creating a default title
Merge branch 'static-pages'

Merged to continue working in the tutorial
Started new layout - Nav

New layout started, navigation bar added.
Home view modified

New layout
Home image fixed

Added rails.png fo showing it in the home view
CSS Added
Partials added

Partials added: header, footer and shim
Home title fixed
Contact page added
Links added

Header and footer links have been added with their tests. New contact page have been also added.
Login page added

New controller User have been added for loging process.