Added classes for main architecture of demand elasticity task and tests for range class.
Added to functionality checking of exception.
Refactoring architecture of classes.
Changing hierarchy of project's packages.
Fixed checkstyle.
Unnecessary casts have been removed and all tests have been matched to the template.
Using strategy pattern has been improved.
Merge pull request #61 from evgeniy-izutov/lab1-tdd-demand-elasticity

Изутов - Лабораторная работа #1