Added vendor name to composer.json

Error from packagist: The package name bootstrap-glyphicons is invalid, it should have a vendor name, a forward slash, and a package name. The vendor and package name can be words separated by -, . or _. The complete name should match "[a-z0-9]([_.-]?[a-z0-9]+)*/[a-z0-9]([_.-]?[a-z0-9]+)*".