使用Laravel 4使用对routes.php的重写规则配置干净的URL

Recently I've started learning Laravel , I have none experience with framework before. I'm encountering the following problem .I'm trying to configure the .htaccess file so I can have clean URLs but the only thing I get are 404 Not Found error pages. I have created a virtual host - you can see below the configuration file - and changed the .htaccesss file on the public directory.

/etc/apache2/sites-available

ServerAdmin webmaster@localhost

DocumentRoot /var/www
<Directory />
    Options FollowSymLinks
    AllowOverride all
</Directory>
<Directory /var/www/>
    Options Indexes FollowSymLinks MultiViews
    AllowOverride all
    Order allow,deny
    allow from all
</Directory>

ScriptAlias /cgi-bin/ /usr/lib/cgi-bin/
<Directory "/usr/lib/cgi-bin">
    AllowOverride all
    Options +ExecCGI -MultiViews +SymLinksIfOwnerMatch
    Order allow,deny
    Allow from all
</Directory>

ErrorLog ${APACHE_LOG_DIR}/error.log

# Possible values include: debug, info, notice, warn, error, crit,
# alert, emerg.
LogLevel warn

CustomLog ${APACHE_LOG_DIR}/access.log combined

Alias /doc/ "/usr/share/doc/"
<Directory "/usr/share/doc/">
    Options Indexes MultiViews FollowSymLinks
    AllowOverride all
    Order deny,allow
    Deny from all
    Allow from 127.0.0.0/255.0.0.0 ::1/128
</Directory>

.htaccesss file:

laravel/public

RewriteEngine On
RewriteBase /
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule . /index.php [L]