I released an update for CRM REST Builder to add support for CRM 2015. The previously versions used the SDK.Metadata.Query sample code from the 2011 SDK to access the entity and attribute metadata, this has now been replaced with the Sdk.Soap.js library (Sdk.RetrieveMetadataChanges) and will work in 2011, 2013, and 2015.
In order to support 3 versions I needed to split into 2 different managed solutions for installation. The updated v126.96.36.199 version will work on CRM 2011 and 2013 as it was exported from a 2011 organization. This solution won't be importable to CRM 2015 do to the restrictions that are in place by the system; only solutions exported from 2013 or later can be imported. The v188.8.131.52 version will be the version you will want if you are running CRM 2015. Both versions will upgrade the existing solution in place. If you are upgrading from 2013 to 2015 you should install v184.108.40.206 after doing so in order to continue use. Currently the v220.127.116.11 and v18.104.22.168 code bases are identical.
I've also added the option to assign the skip operator when creating a RetrieveMultiple request.
Download the latest version from CodePlex: