Add support for additional extensions (pgtap)

[rngadam]

I filed a support for Heroku PostgreSQL to add pgtap (http://pgtap.org/documentation.html)

but maybe this is easier and more relevant to do in this buildpack.

• How would I go about adding extensions to the buildpack?

[rngadam]

OK, I'm able to build the extension separately:

heroku ci:debug and then:

git clone https://github.com/theory/pgtap.git  
cd pgtap 
make
#make installcheck
make install

[rngadam]

I made this part of app.json:

{
  "environments": {
    "test": {
      "env": {
      },
      "buildpacks": [
        {
          "url": "https://github.com/heroku/heroku-buildpack-ci-postgresql"
        }
      ],
      "scripts": {
        "test-setup": "./heroku-test-setup.sh",
        "test": "cd server; ./test.sh $DATABASE_URL"
      }
    }
  }
}

heroku-test-setup.sh is:

git clone https://github.com/theory/pgtap.git
cd pgtap
make
#make installcheck
make install
cd ../server
./setup.sh $DATABASE_URL

[mping]

Would be great to be able to install postgis too. Unfortunately, postgis requires a couple other extra libs.