add tests for content update method with objects containing null, string, and boolean values
add tests for content update method with objects containing null, string, and boolean values

grasshopper-cms/grasshopper-core-nodejs,mjmostachetti/grasshopper-core-nodejs,grasshopper-cms/grasshopper-core-nodejs,Solid-Interactive/grasshopper-core-nodejs,Solid-Interactive/grasshopper-core-nodejs,mjmostachetti/grasshopper-core-nodejs