Feature/make collection configurable

This commit adds more configuration options to the
FormCollection-ViewHelper.

The hard-coded fieldset-wrapper is now configurable as is the hard-coded
legend as well as the hard-coded position and template of the
template-provider. The defaults have been set to the currently
hard-coded values, so that no BC-break should happen.

Also the behaviour of the template-renderer has been changed in so far
as the template is now rendered using the collection-object and not the
content of the collection-object

THis might be a case of BC-Break in edge-cases but the current
default-behaviour as provided by the unit-tests is not broken.

No tests have been changed, there have only been additions

This PR is a follow-up to #5565