Support SearchItems endpoint

Upgrade request-promise to v4 (solving issue recombee#10)

Add logic parameter to recommendation endpoints. Use HTTPS as default.

additionalData for interactions, returnAbGroup for recommendation end…

…points

Add recommId parameter to add interaction requests

Support image and imageList item property types

Use new recommendation endpoints

Added parameters amount,price,profit to AddPurchase and amount,price …

…to AddCartAddition

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.