update stemcell 3421.9 and concourse 3.2.1

update to trusty 3421.4, garden-runc 1.8.0, concourse 3.1.1

update to Concourse 3.0.1 and latest stemcell

bosh environment was hardcoded, needs to be env var, which user provides

fix a comment

refactoring to better use ops files to support bosh CA

use ops file to handle difference in way static IP for web front end is done on each IaaS

use ops file to handle difference in way static IP for web front end is done on each IaaS

use jq to set AZURE_STORAGE_KEY

add concourse deployment w/ BOSH created cert/key

changes after "team dogfooding"

Concourse version 2.7.1 -> 2.7.4

clearify cfj installation, IaaS specific helpers for Concourse

cleaned up some variable names

mkconcourse helper needs to be per IaaS since the stemcell is different per IaaS