Add separate install documentation

Signed-off-by: Zack Cerza <zack.cerza@inktank.com>
Rewrite description and overview

Signed-off-by: Zack Cerza <zack.cerza@inktank.com>
Add "Provided utilities" section

Signed-off-by: Zack Cerza <zack.cerza@inktank.com>
Add "Choosing machines for a job" section

Signed-off-by: Zack Cerza <zack.cerza@inktank.com>
Remove old install instructions

Signed-off-by: Zack Cerza <zack.cerza@inktank.com>