Boot Manager LLM Logging

The log data from the Boot Manager is written to /var/opt/cray/log/bm-yyyymmdd. If the -L command line option is used with the bootmanager command or if LLM is not enabled, Boot Manager reverts to legacy logging, which writes log data to /var/opt/cray/log/bm.out. This is a less satisfactory logging method because each Boot Manager restart creates a new log and moves the previous log to bm.out.1. A third restart can possibly cause recent log data to be lost.