git-init-shared: Allow adding users to ACLs subsequently

git-init(1) allows users to safely reinitialize a git repository. This
is useful, for example, if new permissions are set with --shared.

This commit adds similar functionality to git-init-shared(1) by not only
setting the right ACLs on the toplevel directory (and relying on ACL
inheritance through the default entry), but also making sure that the
correct rights are set for all files that already exist in the
repository.

Where before a user had to run the right 'setfacl' invocation themselves
to add a new user to the access lists, now the same is possible by
simply invoking git-init-shared(1) again with the right user. For
example, the following invocation adds access to both 'foo' and 'bar':

	git init-shared repo/ foo
	git init-shared repo/ bar

0 files changed, 0 insertions, 0 deletions