bump grunt-contrib-compress dependency

grunt build is crashing with :

```
Running "compress:app" (compress) task

Done, without errors.

Error: Process exited before Archiver could finish emitting data
  at [object Object].<anonymous> (/noflo-ui/node_modules/grunt-contrib-compress/node_modules/archiver/lib/archiver/core.js:79:13)
  at process.g (events.js:180:16)
  at process.EventEmitter.emit (events.js:117:20)
  at process.exit (node.js:707:17)
  at tryToExit (/noflo-ui/node_modules/grunt/node_modules/exit/lib/exit.js:17:15)
  at Object.exit (/noflo-ui/node_modules/grunt/node_modules/exit/lib/exit.js:34:3)
  at Object.task.options.done (/noflo-ui/node_modules/grunt/lib/grunt.js:154:14)
  at Task.<anonymous> (/noflo-ui/node_modules/grunt/lib/util/task.js:280:25)
  at /noflo-ui/node_modules/grunt/lib/util/task.js:227:11
  at process._tickCallback (node.js:415:13)
```

It turns out it has been fixed upstream :

https://github.com/gruntjs/grunt-contrib-compress/issues/80

Available in grunt-contrib-compress 0.9.1
Merge pull request #311 from djdeath/fix-compress-task

bump grunt-contrib-compress dependency
Revert "bump grunt-contrib-compress dependency"
Merge pull request #313 from noflo/revert-311-fix-compress-task

Revert "bump grunt-contrib-compress dependency"
noflo-node-inspector: fix attached() method not being called by Polymer
Merge pull request #315 from djdeath/empty-node-inspector-fix

noflo-node-inspector: fix attached() method not being called by Polymer