adding --privileged resolved issue with ES failing on startup

[ewilansky]

I don't know if this was caused by a recent Docker update, but I ran into an issue where ES was starting for a second and then crashing. This was happening repeatedly with no clear reason in the logs. In troubleshooting I added --privileged as one of the docker run parameters and that resolved the issue. If you concur with this finding, you might want to add that to your docker run instruction.