This is a Composer-based installer for the Reservoir Drupal distribution.
$ composer create-project acquia/reservoir-project MY_PROJECT --stability=alpha
Composer will create a new directory called MY_PROJECT containing a docroot directory with a full Reservoir codebase therein.
If you peek at the .gitignore we provide, you'll see that certain directories, including all directories containing contributed projects, are excluded from source control.
When you set up the project, Composer will create a file called composer.lock, which is a list of which dependencies were installed and in which versions. Commit composer.lock to source control! Then, when your colleagues want to spin up their own copies of the project, all they'll have to do is run composer install, which will install the correct versions of everything in composer.lock.