#000 - Fix Rails logging.

1. Development server no longer logs into /tmp/debug.log. Removed stale
   log4j.xml files from gadgets engines. It will now be in server/go-server.log
   and DEBUG logs are turned on by default.

2. For production, RAILS_LOG_LEVEL environment variable is introduced. It sets the
   log level. However, that decides what Rails sends to Log4J.  Log4J has its own
   level (in log4j.properties) which decides what it appends to the file appender.
   Usually these two need to be in sync. You can set one to a high level and the
   other to a lower logging level and the lower one will win (meaning, WARN will
   be chosen instead of INFO instead of DEBUG, etc).