###Status Tested by me on magento 2.0.something
Copied this code into another module (changed module name) and seem to work fine on magento 2.1.3
Do not expect this module to be updated/bugg fixed/altered for any specific magento version
###Purpose adds posibillity to search categories the same way as products
###Example Find all categoriese with url_key starting with an "a"
/V1/categories/search?searchCriteria[filterGroups][0][filters][0][field]=url_key&searchCriteria[filterGroups][0][filters][0][value]=a%25&searchCriteria[filterGroups][0][filters][0][conditionType]=like