Update installation instructions

[pietercolpaert]

• Installation instructions should be updated to apache 2.4.
• pagodabox should be removed as since an update at pagoda, it doesn't work anymore

[brechtvdv]

php5-mcrypt has to be installed and enabled too

[coreation]

Yes, good call. Although in next versions of Laravel this won't be necessary anymore :).

[Dobbelsteen]

Should I add 'php5-mcrypt' to the docs then? Seems like you will be using Laravel 4.x for some time still

Edit: I'll add it anyway

[coreation]

@pietercolpaert what instructions should there be added to comply with Apache 2.4?