ProAss2:
makeCacheMatrix:
	* returns an object containing 3 methods
		1. original_matrix - returns original matrix
		2. set_inverse - calculates inverse of matrix and caches it.
		3. get_inverse - gets cached inverse of matrix.

cacheSolve:
	* returns cached inverse of matrix if it exists.
	* calculates the inverse of a matrix and returns it if inverse isnt cached.