docs(ee/docker) updates to Docker EE instructions
docs(ee/docker) updates to Docker EE instructions

* revised RBAC instructions
* formatting for Docker FAQs
* re-order Docker install sections
* add trial user/trial instructions for Docker
* removing references to older versions from Docker instructions

From #634
Mashape/getkong.org,Mashape/getkong.org,Mashape/getkong.org