Multiple first-boot fixes

- Remove apt-get update, to avoid conflicting with users who adopt
  cloud-init (which also does this). It was broken for a long time so
  users are not typically expecting us to handle this at the moment.
- Generalize SSH host key regeneration to handle all types which are
  already present in the image (the old code missed some newer elliptic
  curve types), and more completely remove all traces of any SSH1 RSA
  key (those are insecure).
Remove defunct embed-kernel.sh script

This was only used for the transition from the v1beta16 API to the v1
API, and is no longer relevant. Removing this simplifies life for new
image providers who don't mistakenly assume they need to package or ship
this.
Merge pull request #125 from jkaplowitz/firstboot-fixes

Multiple first-boot fixes
Merge pull request #126 from jkaplowitz/remove-embed-kernel-sh

Remove defunct embed-kernel.sh script
Bump version to 1.1.8
Merge pull request #127 from jkaplowitz/master

Bump version to 1.1.8
Merge pull request #124 from illfelder/master

Enable network-online at boot and removed dead code
Merge pull request #128 from illfelder/master

Added shutdown script logging file
Merge pull request #129 from illfelder/master

Insure network is online for startup scripts
Merge pull request #130 from illfelder/master

Changed warning message for using shutdown script
Bump version to 1.1.9