Add recommId parameter to add interaction requests

Support image and imageList item property types

Use new recommendation endpoints

Merge branch 'master' of https://github.com/Recombee/python-api-client

Added support for view portions

Support returnProperties and includedProperties parameters of ListIte…

…ms and ListUsers. Send User-Agent HTTP header. Use POST for recomm requests. Use artificial default value for parameters in order to allow sending null value.