Properly Escape User's Name in PusherChatWidget.js

Properly Eescapes activity.actor.displayName. Previously, if the user's name was 'Liam O'Connor' it would become 'Liam O\'Connor'.
Now replaces only single quotes
Merge pull request #13 from Mulletfingers999/patch-1

Properly Escape User's Name in PusherChatWidget.js