Merge pull request buildpacks#371 from buildpacks/platform/0.12

Finalize Platform 0.12

Merge pull request buildpacks#371 from buildpacks/platform/0.12

Finalize Platform 0.12

Merge pull request buildpacks#354 from buildpacks/platform/0.11

Finalize platform/0.11

Merge pull request buildpacks#326 from buildpacks/buildpack/0.9

Finalize buildpack/0.9

Merge pull request buildpacks#326 from buildpacks/buildpack/0.9

Finalize buildpack/0.9

Merge pull request buildpacks#303 from buildpacks/platform/0.9

Finalize Platform API 0.9

Merge pull request buildpacks#302 from buildpacks/buildpack/0.8

Finalize Buildpack API 0.8

Merge pull request buildpacks#282 from buildpacks/extensions/project-…

…descriptor/0.2

RELEASE: Project Descriptor 0.2

Merge pull request buildpacks#272 from buildpacks/platform/0.8

Finalize Platform API 0.8

Merge pull request buildpacks#273 from buildpacks/buildpack/0.7

Finalize Buildpack API 0.7