Feature request from allanpaiste, posted on GitHub Aug 04, 2016
Currently it's not possible to create an 'image' EAV attribute for category as the code in many places has been hardcoded to talk only with attribute that is explicitly been named 'image'.
This PR addresses that problem by steering the code towards more generic approach to the whole situation by detecting all matching attributes via backendModel check.
Related issue: https://github.com/magento/magento2/issues/5438