Adding archive directive to exclude tests, docs and design from the composer archive

`composer archive` would fail because one of the test files containing
multibyte characters in the file name.

I ran into this issue while building a static composer/satis repository. Including the webdav component would cause satis to fail because apparently, there is an issue with phar files and multibyte characters.

I opened a satis issue (https://github.com/composer/satis/issues/70) and proposed a patch. However, it was suggested that I add the archive directive to the package.

The static repository will speed up the update process for our developers significantly. This may solve your issue #1. You might also consider building a satis repository for all zetacomponents just like zend framework did.