change slack notification format

This moves to using attachments for the notifications - should give a much prettier version of build and deploy statuses
Includes deploy targets in deploy messages
Includes green/red indicators for success/failure of builds/deploys

Aw sorry I thought I had deleted that for the upstream commit. I'll fix that. Robbie is just a hubot. I'll remove that bit and resubmit the pr tomorrow. 

> On Aug 30, 2014, at 6:42 PM, Spencer Herzberg <notifications@github.com> wrote:
> 
> In run.sh:
> 
> > @@ -3,6 +3,18 @@
> >  AVATAR=''
> >  USERNAME=''
> >  
> > +if [ -n "$DEPLOY" ]; then
> > +  if [ -n "$ROBBIE_URL" ]; then
> @emaland what is ROBBIE_URL used for? Who sets this?
> 
> —
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