Rubyisms

A little refactoring to make use of some ruby conventions within the Character class.
Added some basic specs using rspec for the Character object.
Notes inline.
Eliminate the need to require a user of this object to call `obj.set_age` to do the calculation. This calculates on the fly but does have a slight drawback. If you call `obj.age` before the terms property is set to what you want it to be, until that object is destroyed and recreated it will always return the value with terms = 0. To get around that just drop the `@age ||=` part and only return the calculation every time.