FormCollection: Set twb-layout on template element

The twb-layout was not propagated from the TwbBundleForm to the template
element that is generated by the TwbBundleFormCollection. This resulted
in incorrectly rendered template when e.g. horizontal layout was used.
Merge pull request #62 from Maners/collection-template

FormCollection: Set twb-layout on template element
Update composer.json
Update README.md
Update README.md