Add more 1.2.1 changes to changelog
Add more 1.2.1 changes to changelog

rwhitmire/messenger,dieface/messenger,freakynit/messenger,leegilon/messenger,npmcomponent/HubSpot-messenger,rwhitmire/messenger,HubSpot/messenger,dieface/messenger,giobero999/messenger,leegilon/messenger,HubSpot/messenger,giobero999/messenger,npmcomponent/HubSpot-messenger,freakynit/messenger