Add changelog and acknowledgements for 0.13 release
Add changelog and acknowledgements for 0.13 release

kinow/jira,m42e/jira,systemadev/jira-python,kinow/jira,m42e/jira,VikingDen/jira,dbaxa/jira,tsarnowski/jira-python,dwmarshall/pycontribs-jira,tsarnowski/jira-python,pycontribs/jira,milo-minderbinder/jira,milo-minderbinder/jira,rayyen/jira,awurster/jira,akosiaris/jira,coddingtonbear/jira,VikingDen/jira,rayyen/jira,pycontribs/jira,coddingtonbear/jira,dbaxa/jira,systemadev/jira-python,akosiaris/jira,jameskeane/jira-python,dwmarshall/pycontribs-jira,awurster/jira,stevencarey/jira,jameskeane/jira-python,stevencarey/jira