Ubuntu release not present anymore bump to 14.04.5

[breemay]

The version 14.04.4 of ubuntu-server used in the example does not seem to be present on the server any more.

breemay@RedCloud ~/tmp/udacity/dev-ops/packer-templates $ packer build -only=virtualbox-iso application-server.json
virtualbox-iso output will be in this color.

==> virtualbox-iso: Downloading or copying Guest additions
    virtualbox-iso: Downloading or copying: file:///opt/VirtualBox/additions/VBoxGuestAdditions.iso
==> virtualbox-iso: Downloading or copying ISO
    virtualbox-iso: Downloading or copying: http://releases.ubuntu.com/trusty/ubuntu-14.04.4-server-amd64.iso
    virtualbox-iso: Error downloading: Error making HTTP GET request: 404 Not Found
==> virtualbox-iso: ISO download failed.
Build 'virtualbox-iso' errored: ISO download failed.

==> Some builds didn't complete successfully and had errors:
--> virtualbox-iso: ISO download failed.

==> Builds finished but no artifacts were created.

[13rac1]

Duplicate of #28