Fix logger

It seems the logger is not configured properly in descriptorParser:

$ tail logs/metrics.log 
SLF4J: Failed to load class "org.slf4j.impl.StaticLoggerBinder".
SLF4J: Defaulting to no-operation (NOP) logger implementation
SLF4J: See http://www.slf4j.org/codes.html#StaticLoggerBinder for further details.

This should be fixed although we are manually sending crashes to the log file.