Delete all unnecessary methods

Deleted method void SaveDB(XMldocument doc) from class User;
Deleted method void SaveDB(XMldocument doc) from class Product;
Merge branch 'master' of https://github.com/zanikoleh/PMI21_TeachingPractice

Conflicts:
	PMI21_TeachingPractice/PMI21_TeachingPractice.v11.suo
	PMI21_TeachingPractice/PMI21_TeachingPractice/Models/Product.cs