Default stabilizer config should use rolling file appender for worker

Added RollingFileAppender as default for Log4j. Made MaxFileSize and MaxBackupFiles configurable via coordinator cli. Default values are 1gb per file and 5 backup files (which creates 6 gb of log data in 6 files at maximum).

This resolves issue #363.

Example usage:
```
#!/bin/sh

# this will configure Log4j to write 100 gb of data in 10 files (1 active log + 9 backups)
log4jMaxFileSize=10gb
log4jMaxBackupIndex=9

boxCount=10
members=16
workers=8
duration=4h

jvmArgs="-Dhazelcast.health.monitoring.level=NOISY -Dhazelcast.health.monitoring.delay.seconds=1"
jvmArgs="${jvmArgs} -Xmx1000m -XX:+HeapDumpOnOutOfMemoryError"

provisioner --scale ${boxCount}

coordinator --memberWorkerCount ${members} \
	--clientWorkerCount ${workers} \
	--duration ${duration} \
	--workerVmOptions "${jvmArgs}" \
	--log4j.maxFileSize ${log4jMaxFileSize} \
	--log4j.maxBackupIndex ${log4jMaxBackupIndex} \
	--parallel \
	large.properties

provisioner --download
provisioner --terminate
```