Merge branch 'fix-readme'
add factory method for vehicle class
fix alloc problem when using factory method
add factory method for car class
add factory method for motorcycle and truck class
fix wrong output title string value
Merge branch 'fix-wrongOutput' into develop
Merge branch 'feature-factoryMethod' into develop
add singleton VehicleList
integrate singleton to view
Merge branch 'feature-singleton' into develop
bump version to v1.2
Merge branch 'release-1.2' into develop