Pull request

Made the changes you requested.  I changed FileOverwriterOutputWriter.java to also print like RollingFileOutputWriter.java Let me know if you want me to revert that.

The new output looks like this:
```
[2014-10-24T15:46Z] os.systemLoadAverage 1.56494140625
[2014-10-24T15:46Z] jvm.heapMemoryUsage.used 269985920
[2014-10-24T15:46Z] jvm.heapMemoryUsage.committed 457703424
[2014-10-24T15:46Z] jvm.nonHeapMemoryUsage.used 30605072
[2014-10-24T15:46Z] jvm.nonHeapMemoryUsage.committed 31260672
[2014-10-24T15:46Z] jvm.loadedClasses 4145
[2014-10-24T15:46Z] jvm.thread 32
[2014-10-24T15:46Z] tomcat.requestCount 13
[2014-10-24T15:46Z] tomcat.requestCount 0
[2014-10-24T15:46Z] tomcat.errorCount 1
[2014-10-24T15:46Z] tomcat.errorCount 0
[2014-10-24T15:46Z] tomcat.processingTime 738
[2014-10-24T15:46Z] tomcat.processingTime 0
[2014-10-24T15:46Z] tomcat.bytesSent 96661
[2014-10-24T15:46Z] tomcat.bytesSent 0
[2014-10-24T15:46Z] tomcat.bytesReceived 0
[2014-10-24T15:46Z] tomcat.bytesReceived 0
[2014-10-24T15:46Z] application.activeSessions 0
```

Again, we use this in all our AWS deployments  and consume logs into CloudWatch (and graphite).