change TripCalculator Singleton Exception handling
add new exception handling
add test for new calculation
add test, reduced calculation method to one
add trip tests
create TripModelTest class and methods
remove TripModel main method
add vehicle tests
Merge remote-tracking branch 'origin/master'

Conflicts:
	src/main/java/tripcalculator/bl/TripCalculator.java
	src/main/java/tripcalculator/bl/TripModel.java
	src/test/java/TripCalculatorTest.java