Validate outgoing AS objects

[silverbucket]

Currently outgoing AS objects (those generated by irc2as specifically) are not being validated against the sockethub schemas. This means we can easily have inconsistencies with objects sent from sockethub to the client as we continue to improve and increase validation checks with object sent from the client to sockethub.

This was noticed when addressing #679 (irc2as generated AS object with an invalid actor type), and was the start of a larger code overhaul that I'm working on now.

[raucao]

Sorry, just found this in the logs, but don't know from what it was:

  sockethub:validate:oJyy2NISvyXrdPA_AAAp applying schema validation for message +0ms
  sockethub:middleware:message Error: /target: must have required property 'type'
  sockethub:middleware:message     at Array.<anonymous> (/home/basti/src/sockethub/sockethub/packages/sockethub/dist/middleware/validate.js:60:22)