Added libncurses5-dev and removed nokogiri depdencies

I removed the nokogiri depdencies because nokogiri isn't a part of the standard libary. Besides I added the libncurses5-dev package it is required by the [curses](http://www.ruby-doc.org/stdlib-1.9.3/libdoc/curses/rdoc/Curses.html) module which is a part of the standard libary.