Optimize imports in Application.java.

Seems like IntelliJ IDEA doesn't handle imports of viewm.html.* very well.
When importing with a '*' it marks all usages of the view classes as errors.
But with explicit imports the errors are removed.
Change success message when adding games.

Also use the flash scope in a smarter way!
Make the success message dismissible.
Replace StandingsCalculator's internal ObjectMapper with JSONUtils.
Extract login actions to their own controller.
Secure all actions in the application controller.

Some had earlier been missed and allowed for non logged in users
to reach and/or to call them.
Remove unused controller method Application.player(String).

Also remove associated routes configuration.
Initial support for requiring a selected game group to navigate the app.

Created a specific controller for game groups (GameGroupPortal).
Moved the gameGroups action there from Application.
Created new interceptor that checks for a selected gamegroup in the
current session scope. If none is found it redirects the user to the
gameGroups route.
Printed a warning message in the gameGroups view when no groups
are found.
Fix bug where GameGroup.insert(String) doesn't save the new group.
Make it possible to add GameGroups.