Set PCLZip as the default zip class

[ivanlanin]

Since it's already available since #140, can we change our default zip class from PHP's ZipArchive to PCLZip? This will reduce our dependencies and will enable PHPWord for developers that can't use ZipArchive. We will be more "pure PHP library".

[Progi1984]

Personnally, I agree. But we need to add documentation for changing this setting.

[ivanlanin]

We just need to update this part :)

[Progi1984]

Affirmative :)

[ivanlanin]

I've done some testing and I found out that it's much slower when we use PCLZip. I drop this issue for now and leave ZipArchive as default.