[jb] MR2 Get all the logs

Currently if once clicks on the jobbrowser log link (e.g. http://bigtop:8888/jobbrowser/jobs/job_1365541374898_0008/single_logs) a typical response would contain

Log Type: syslog
          
            Log Length: 57845
          
            Showing 4096 bytes of 57845 total. Click 
            here
             for the full log.

Of course one can NOT click on it (since it is just a text that historyserver returned) but it would be nice if jobbrowser could get a complete set of logs from HS

the only
difference in the URIs would be a ?start=0
tucked at the end. Like this:

http://ip.internal:19888/jobhistory/logs/ip.ec2.internal:50490/container_1365541374898_0001_01_000001/job_1365541374898_0001/hue/syslog/?start=0