Added "Scala for the Impatient"
Added "The Quest for Artificial Intelligence: A History of Ideas and Achievements"
Added Stef's Free Online Smalltalk Books
Added "Apache Jakarta Commons: Reusable Java Components"
Added "Search User Interfaces"
Added "Big Data Now: Current Perspectives from O'Reilly Radar"
Added "The Z Notation: A Reference Manual, Second Edition"
Merge pull request #519 from alexanderfefelov/master

A few books added