hasLightblueErrors can return true when getLightblueErrors returns null

In AbstractLightblueResponse, hasLightblueErrors checks to see if the status is equal to "partial" but doesn't look to see if "errors" actually exist in the json. 

So I have to do `if(getLightblueErrors() != null)` rather than `if(hasLightblueErrors())`, making that method pretty pointless