Modifications of Dal and Entities

Chages:
	- Validation added to database level
	- Added validaion tests
	- Added crud tests
	- Some errors in schema corrected
Merge branch 'master' of https://github.com/CBO-Bank-Group/Credit-System

Conflicts:
	src/CBO-Bank-Credit-System/CBO.CS.Dal.Tests/CrudTests.cs
	src/CBO-Bank-Credit-System/CBO.CS.Dal/Helpers/RepositoryFactories.cs
	src/CBO-Bank-Credit-System/CBO.CS.Dal/Models/CreditSystemModel.edmx