Merge pull request SeleniumHQ#41 from schmunk42/patch-1

updated docker info

OS agnostic switch for copy flags in Makefile

On mac the `cp` flags to use are `-pR` but on Linux it's `-rT`. This
change will allow the makefile to work on either of those two operating
systems.

/etc/hosts hack no longer necessary since docker >= 1.2.0

Some tiny changes