Add 'dialog' to packages list

When apt is doing things, it periodically throws this error:

debconf: unable to initialize frontend: Dialog
debconf: (No usable dialog-like program is installed, so the dialog based frontend cannot be used. at /usr/share/perl5/Debconf/FrontEnd/Dialog.pm line 76.)
debconf: falling back to frontend: Readline

Here: http://forum.doozan.com/read.php?2,502,506, Gorgon says to add this to the build script:

apt-get install dialog

I wasn't sure where it should fall in the order of packages, so feel free to move it.
Merge pull request #2 from knickers/patch-1

Add 'dialog' to packages list