Adds the allowed properties from the Properties to the
velocity engine
So far, we support, in RuntimeConstant parlance :
VM_LIBRARY
FILE_RESOURCE_LOADER_PATH
RUNTIME_LOG
RUNTIME_LOG_LOGSYSTEM
RUNTIME_LOG_LOGSYSTEM_CLASS
If you are going to use this, ensure you do it *before* setting
the stylesheet, as that creates the VelocityEngine