Set CeylonTool.toolLoader manually.

As ceylon.build is now using ceylon.build.runner that loads manually build module using JBossModules, modules:
 - com.redhat.ceylon.compiler.java
 - com.redhat.ceylon.compiler.js
 - ceylon.runtime
were not loaded which means that call to CeylonTool.start was failing at runtime.

Solution is to manually load those modules at runtime when needed by setting the right ToolLoader for CeylonTool before using it.