Moved many things to Login.js

Resolves #1112.

http://jenkins.buttonweavers.com:8080/job/buttonmen-AdmiralJota/399/

In addition to the tests for whether or not the player is logged in, I also moved a bunch of common code from the ```Foo.showFooPage()``` and ```Foo.arrangePage()``` methods in the individual files to ```Login.arrangeHeader()``` and ```Login.arrangePage()``` so that it can be shared. 

Most pages don't even need their own ```arrangePage()``` method anymore (so I took them out, just having them call ```Login.arrangePage()``` instead), and there are several pages where we should probably merge ```Foo.showFooPage()``` with ```Foo.getFoo()``` at some point, since there's so little there now.
Do we want to treat the logged-out case this way?  An alternative would be to have Login.showLoginHeader() take two callbacks, `callback` and `loggedout_callback`.  Then if the second argument wasn't provided (`typeof(loggedout_callback) === undefined`), you could do the default "no logged out page" logic.

It seems cleaner to give a particular page an option of saying, i want to show the logged-out user *something*, but not the same thing as the logged-in user.

Thoughts?