git will ignore Sublime Text project files
Avoid problems with 'include' in specs

I discovered that "obj.should include(something)" was not working in our specs.
It has been changed to "obj.include?(something).should == true".
Use 'context' to describe test context in Hash.new spec
Don't use before block with instance var in Hash#reduce spec

Our preferred style is to use RSpec's "let" rather than instance variables.
Fixed typo in Set#filter spec
Make Set#include? spec pass consistently
Added specs for Hash.[]
Added Hash#store (to match built-in Ruby Hash)
Added YARD summary of Hamster::Hash