Register module against Language Util.
Prepare module.xml for Language change.
Updated module descriptors and added one for javax.lang system dep of the compiler
JBossRuntime: make the module loader returned of type CeylonModuleLoader
CeylonModuleLoader: moved the language module runtime setup to a linear method to avoid deadlocks

in preloadModule it was causing ConcurrentClassLoader deadlocks...
CeylonModuleLoader: load ceylon.language module first, then additional modules on demand

This avoids a deadlock by making sure the ceylon.language is loaded first, since it's
required by all other modules.
It also makes sure that all runtime module info will be properly lazy loaded as the
jboss modules system lazy loads them
turns out the compiler depends on ceylon.language at runtime via reflection
CeylonModuleLoader: no NPE when module is null, and turn "null" version into null for the default module