Added ECurrencies enumeration
Removed unused class
Revert "Removed unused class"

This reverts commit 3ade8fb9f1a7d7570442f08130a493cfe6324f8b.
Added Price class
Added Exchanger class
Added IEquatable and IComparable interfaces
Added Addition operations
Small cosmetic changes
Added Comparison operations
Added serialization
Testing new functionality
Rename region
Cosmetic improvements
Fixed bug with null reference
Added test's
Added comments and some cosmetic changes
Merge pull request #1 from haritowa/develop

Complete all subtasks of "Работа No1. Строки, числа, отношения объектов"