Create sample apps with dockerfiles, hooks, etc

[aemengo]

In light of buildpacks/rfcs#173, sample applications should be created with these new buildpack constructs: App Specified Dockerfile, Hook TOML, etc.

[cmoulliard]

Is the following builder structure correct ?

@sclevine @natalieparellano @aemengo

[natalieparellano]

I think ext.toml should be extension.toml. I don't think build.ext.toml and launch.ext.toml are included in the RFC (they were just talked about).

[natalieparellano]

Please see buildpacks/lifecycle#709 (comment) for an initial take on this issue.

[cmoulliard]

(they were just talked about).

I saw them from a comment of Javier Romero. will remove them and add also run.Dockerfile and build.Dockerfile

[cmoulliard]

Structure updated