Work towards #56: Splitting up the README

I did the job and splitted up the readme, hopefully everything was
splitted correctly...

factory-method/index.md

@@ -0,0 +1,19 @@
+---
+layout: pattern
+title: Factory Method
+folder: factory-method
+categories: creational
+tags: pattern_tag
+---
+
+**Intent:** Define an interface for creating an object, but let subclasses
+decide which class to instantiate. Factory Method lets a class defer
+instantiation to subclasses.
+
+![alt text](./etc/factory-method_1.png "Factory Method")
+
+**Applicability:** Use the Factory Method pattern when
+
+* a class can't anticipate the class of objects it must create
+* a class wants its subclasses to specify the objects it creates
+* classes delegate responsibility to one of several helper subclasses, and you want to localize the knowledge of which helper subclass is the delegate