Added amazon_utils.h.

Header contains declarations and definitions which may be helpful to either take-home problem.
Added missing semicolon to Node typedef

Fixes compilation error
Added amazon_problem1.h

Implements framework for solving Amazon's take-home problem 1
Expanded comment for Amazon_Problem1::checkBSTCharacteristics(...)

Briefly outlines method logic and gives reference for more info
Added Amazon_Problem1 method definitions

Defines class methods for finding the largest BST of a given root
Added amazon_problem1 makefile

Automates amazon_problem1 compilation. Still not complete (no clean etc) but fine for now