Post Comment should return error when non-existing blobHandle is passed

[Vadim-Bulavin]

1. Post comment

curl -X POST --header 'Content-Type: application/json' --header 'Accept: application/json' --header 'Authorization: SocialPlus TK=eyJ0eXAiOiJKV1QiLCJhbGciOiJIUzI1NiJ9.eyJhdWQiOiIzcjNGcnhjNVJLdFxuRmFjZWJvb2tcbjEzNDQ4MDkzMDg5NjA4ODAiLCJpc3MiOiIzdm4tNUJOZUFnV1xuZWMxNjY1YTQtOTIwZC00NDQ5LWI4YTAtNDllZDM3NGQ0MjkwIiwiZXhwIjoxNTI1Njg2ODM2fQ.6XE1Xh5Rslung-x2R1DRWlbd1Fr1cXJumIaCi2rGNSA' -d '{
  "text": "1",
  "blobType": "Image",
  "blobHandle": "B2GYegS92af4uSBuTrSjEKM7"
}' 'https://ppe.embeddedsocial.microsoft.com/v0.7/topics/3qoGqeV0IVZ/comments'

Expected: receive error response, comment is not created.
Actual: comment is created, response code 201 is received with body:

{
  "commentHandle": "3qj2rE5EAdx"
}