set current thread classloader for scalate

scalate decides whether it runs inside an OSGi framework based on the
current thread classloader
start a \BlueLaTeX server for tests

embryonic way of starting the server
rename methods for (un)authenticated actions

Actually, the semantics is that the request is authenticated, it can be
achieved through a logged in user, but it can also be (in the future) a
request authenticated and authorized with some other service or with
OAuth.
return user context when authenticated

actually, it is not necessary to load the \BlueLaTeX specific user
information when getting the current authenticated, instead we just need
to know the user name and its roles to decide whether he has the rights
to work with a resource