Fix regression caused by using newer version of Grape
Created by: dblessing
This commit fixes the regression caused by using a newer version of Grape and Grape entity. This solves Issue #4023.
I don't know if there was a particular reason for changing Grape version (commit 083d6656). If there is no compelling reason to change the Grape version, I recommend we revert that change with this PR to solve the current regression with raw content in the API. This regression breaks tools that integrate with the API.