#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 will (meaning, WARN will
   be chosen instead of INFO instead of DEBUG, etc).
#000 - Handle empty string for RAILS_LOG_LEVEL.
#000 - Fix null check in HostNameValidator.

Was showing up as a 500 Internal Server error when you clicked 'Send Test Email'
in Server Configuration page, without entering any hostname.
Merge pull request #605 from arvindsv/fix_empty_hostname_validation

#000 - Fix null check in HostNameValidator.
Merge pull request #600 from arvindsv/fix_rails_logging

#000 - Fix Rails logging.