refactor(sample.xmi): change sample to newer examples

tdt4250.spp.html/src/tdt4250/spp/html/source/SampleSpp.xmi

tdt4250.spp.html/src/tdt4250/spp/html/target/NTNU.html

tdt4250.spp.model.edit/plugin.properties

.../src/tdt4250/spp/provider/SpecialisationItemProvider.java

tdt4250.spp.model/src/tdt4250/spp/Course.java

tdt4250.spp.model/src/tdt4250/spp/Program.java

tdt4250.spp.model/src/tdt4250/spp/Specialisation.java

tdt4250.spp.model/src/tdt4250/spp/SppPackage.java

tdt4250.spp.model/src/tdt4250/spp/impl/ProgramImpl.java

...50.spp.model/src/tdt4250/spp/impl/SpecialisationImpl.java

tdt4250.spp.model/src/tdt4250/spp/impl/SppPackageImpl.java

tdt4250.spp.model/src/tdt4250/spp/util/SppValidator.java