Composer allows you to use custom plugins to add extra behaviour to install, update, uninstall, ... events. The first time I "discovered" this extra functionality was during a talk by Toon Verwerft (@toonverwerft) about GrumPHP, a PHP QA tool.
GrumPHP is a Composer plugin which installs a couple of GIT hooks in your repository, which perform QA checking on your project.
The copying of the GIT hooks is actually pretty easy using a plugin, you just attach event handlers to certain Composer package/script events such as install, update and uninstall.
I made two repositories which display how easily you can enforce git hooks for all your projects by requiring 1 extra package.
You can easily customise which GIT hooks should be enforced by forking my repository and placing your own GIT hooks in the hooks directory.
Note: If you want, you can still bypass commit checking by adding the –no-verify option to your commit command.