Runthrough highlighting some hardcodes

[JimCircadian]

In running setup_terraform.py noticed that some hardcoding was present thanks to reliance on terraform/backends.tf for defaults on the storage account.

• [x] Sorted out some backend var amendments for providing initial terraform state storage dynamically
• [x] Removed common and sorted dynamic storage accounts
• [x] Added environment var
• [x] Updating and running through README instructions.

[JimCircadian]

Updated for invocation of the initial terraform state via:

./setup_terraform.py -v \
  -i [[redacted]] \
  -s [[redacted]] \
  -g [[redacted]] \
  -rg [[redacted]] \
  -sa [[accountname]] \
  -sc [[containername]]

terraform init -backend-config=backend.secrets \
  -backend-config='storage_account_name=[[accountname]]' \
  -backend-config='container_name=[[containername]]'

It doesn't really simplify things, but means that out of the box runs will work. I'll add this to the readme.

[JimCircadian]

Removing the use of the common module, which is hardcoding resource names and locations. The absence of global vars is intentional, and this is an antipattern for achieving the same result across modules which is now tripping up portability to another tenant.