Use augeas instead of echo / sed to edit ssh/sshd configuration

Implements: blueprint merge-dib-hadoop-elements
Change-Id: I1f2f8c3d69d879660aabf6f72560e6d22012a0a5
Merge Ubuntu and Fedora instructions for ssh/sshd setup

Implements: blueprint merge-dib-hadoop-elements
Change-Id: Iabcb30abee4ccf79235aeb113eaa414a44835693
Merge Ubuntu and Fedora instructions for first-boot

Implements: blueprint merge-dib-hadoop-elements
Change-Id: Ie795be74adbbc6c742b2ffeb6e93ef3b93781aa3