Implemented logger interface, mock logger for ViewModel.

Added first ViewModel tests. ViewModel constructor was divided into
smaller parts
Logged events clicking on button "Convert" and changing src and dst colors
Logged color values and src/dst channels in ViewModel
Logged values of source color on changed focus
Created Infrastructure project and real logger.
Initial implementation getLog and addToLog methods in DatedTextLogger
Date and time were added to the log.
Minor refactoring at the dated logger
Added a class to run all tests ViewModel with the "real" logger
Binding logging logic to graphic form
Fixes according to the comments
Fixed behavior with null logger
Merge pull request #152 from ljaljushkin/lab3_ddd_color_converter

Лялюшкин - Лабораторная работа #3
initial commit
started logger implementation
some tests for logger added
decided to simplify logger
some logger tests refactoring
added one more dateTime test
started to implement logger in viewModel