Fix Ubuntu Install Guide link
Change ntp install to common role
Merge pull request #765 from ageis/develop

Change ntp install to common role
Merge pull request #764 from pemulis/patch-2

Fix Ubuntu Install Guide link
Merge pull request #767 from runasand/develop

Additional updates for install.md
offline backup device

Removed reference the external hard drive and replaced with using a second offline USB tails device as the offline backup
text updates

for the app and monitor servers hardware updated the memory recs to be the size linked to (4GB) instead of 8/16GB.
Merge pull request #768 from dolanjs/hardware-fixes

install and hardware doc updates