Remove hard coded ntp servers in configuration file

Because its not always appropriate to be using pool servers (security
concerns, network reliability, aggressive perimeter firewalling) I have
removed the default ubuntu related server entries.

To ensure the role keeps working OOTB I've made them the default NTP
servers for the role.

This does mean instead of ntp_servers+5 defaults you only have ntp_servers.
NTP peer configuration code and options

Its often handy to keep all the hosts on a network configured as
peers - this adds support for that. If no peers are configured an
empty newline is added on the first run, following runs will only
change the configuration if ntp_peers is changed.
Add ntp_peers to README.md

New option so adding it as an example.
updated variables
merged configuration-for-local-peers
Merge branch 'release/1.1.0'