build: Update to maven-compiler-plugin 3.1.
build: Tweak checkstyle package name format.
build: Format checkstyle suppressions.
ui: Tweak getUriFragment in UserView & RepoView.
ui: Introduce view requests, migrate navigation & setup.
Some Vaadin stuff.. dunno
Remove Vaadin, remove unused, rename to protoweb, reformat to 80 column.