Sponsor logos are not aligned horizontally in grid block

[steffenri]

steps to reproduce

1. go to https://plone.de/services/plone-agentur or the frontpage
2. navigate to the sponsor logos area
   -> Sponsor logos (and their headline) are not aligned correctly

possibly related to #36

[jnptk]

We are now using the logos block for displaying the sponsors, which lead to a small improvement. With #62 the problem will be solved.

[TimoBroeskamp]

This is fixed I think we can close it.