change ui to work with updated endpoint (https://issues.cask.co/browse/C...

...DAP-501)

Update in the UI, based upon changed endpoint:
https://github.com/caskdata/cdap/pull/545/files#diff-887698b13a9e83c3c873f29bf9633f9fR1703
`obj` is not `var`ed... can we just do `workers.push( Ember.Object.create({id : key}));` ?