To issue #385 unit test are added
To issue #385 integration tests to method CalculateVisaDays() are added
Merge remote-tracking branch 'upstream/development' into development

Conflicts:
	AjourBT.Tests/Controllers/ADMControllerTest.cs
	AjourBT/Controllers/ADMController.cs
unit tests fixed
Merge pull request #405 from AnnaStorozhenko/development

To issue #385 calculate visa days