Changes to Create a snippet

removed the request property allOf[subschema #2: Snippet]/creator/allOf[subschema #2: Account]/username

removed the request property allOf[subschema #2: Snippet]/owner/allOf[subschema #2: Account]/username

removed the optional property allOf[subschema #2: Snippet]/creator/allOf[subschema #2: Account]/username from the response with the 201 status

removed the optional property allOf[subschema #2: Snippet]/owner/allOf[subschema #2: Account]/username from the response with the 201 status