Fixes #7096 - Adds STI to templates

This commit converts Ptables to be just another type of Template so it
gets the same features as ConfigTemplate. ConfigTemplate was renamed to
ProvisioningTemplate to reflect UI and the name under it's commonly known.

fixes #9301 - make puppet environment optional for hosts

fixes #10020 - add next-server/filename attrs to provision NIC DHCP record

A host's DHCP record used to be constructed with PXE attributes in
Orchestration::DHCP, but moved to Nic::Managed during 43c4bd7. Nic::Managed
didn't add PXE attributes, so this commit adds these when provision? is set....

Fixes #9362 - Corrected CoreOS mediapath

fixes #9397 - Make usage of @host.operatingsystem in UnattendedController consistent

Changed all host.os to host.operatingsystem

Refs #3809 - Remove cop IndentationConsistency

Refs #8857 - Styling fixes for coreOS boot_files_uri

fixes #8857 - refactor Debian boot_files_uri into parent class to match CoreOS