Add a feature to rewrite the apt sources files

[cb372]

This feature rewrites all references to Ubuntu's EC2 mirrors (e.g. eu-west-1.ec2.archive.ubuntu.com) to point to the canonical repo server (archive.ubuntu.com) instead.

This is designed to be used as a temporary workaround for when the EC2 mirrors break, which happens occasionally.

I've tested it manually by spinning up an EC2 instance using the generated AMI and running install.sh.

[sihil]

Fine - I think the build error is a transient issue related to hashicorp/packer#1539.

One question was the .gitignore change? The CA cert was a .pem at one stage and there might be other reasons to exclude it. The explicitly named one is created by packer, possibly the regex needs to be widened if packer does something else locally with multiple builders?

[cb372]

Yes, on my machine at least, Packer generated a .pem file for each image: ec2_ubuntu-trusty-java7.pem and ec2_ubuntu-trusty-java8.pem.

I can exclude those 2 files specifically if you prefer, but I don't see why we would ever want to commit a .pem file to this repo.

[sihil]

There is a .crt file for the gnm-ca feature. Is actually a .pem.

Can we make it ec2_*.pem?