https://github.com/ademchenko/DependenciesTracker/issues/2

Cover DependenciesTracker by tests
 - added  additiona tests for initially calculating dependent of dependent property.
https://github.com/ademchenko/DependenciesTracker/issues/2

Cover DependenciesTracker by tests
 - remove unused "usings"
Merge remote-tracking branch 'origin/master'

Conflicts:
	DependenciesTracker/DependenciesTracker.Tests/DependentPropertyCalculationsTest.cs