[xenial] Ensures server packages required by ./securedrop-admin install are present on Xenial#4115

Merged

emkll merged 4 commits intofreedomofpress:developfrom zenmonkeykstop:4109-prepare-servers

Feb 15, 2019

Commits on Feb 13, 2019

new role to add server packages required by ./securedrop-admin install
zenmonkeykstop
committed
Updates apt install logic

emkll
authored and
Conor Schaefer
committed
Adds prepare-servers to staging playbook

emkll
authored and
Conor Schaefer
committed
Renames apt version checks in FPF repo install
Conor Schaefer
committed