Add I18N
Merge branch '#129_contacts_example' of https://github.com/sialcasa/mvvmFX into #129_contacts_example

Conflicts:
	examples/mvvmfx-contacts/src/main/java/de/saxsys/mvvmfx/contacts/App.java
	examples/mvvmfx-contacts/src/main/resources/default_de.properties
	examples/mvvmfx-contacts/src/main/resources/default_en.properties