Skip entities which have no friendly_name and haaska_name properties

[sibbl]

I had the problem that initially no entities were found by Alexa and the following was logged: Discovery failed: 'friendly_name'. Turns out that I have an entity in my local setup where friendly_name is not set, for whatever reason.

This PR should skip such entities by simply filtering them. Of course, if theres ahaaska_name` configured, it should work as this is being used when building the response object for Alexa.

[gabrielbratescu]

I have the same problem. Solved it another way, but this may be the better implementation. +1 vote