fix exception handling
add custom weekday exception
Merge remote-tracking branch 'origin/master'

Conflicts:
	src/main/java/tripcalculator/bl/TripModel.java
	src/main/java/tripcalculator/gui/TripCalculatorGUI.java
	src/main/resources/tripcalculator/bl/trips.csv
	src/test/java/TripCalculatorTest.java