Prevent crashes in http-proxy

This closes #1921.

`connect-restreamer` is fundamentally nuts and rather fragile. It also
makes no sense when we can just avoid the issue entirely by putting
`http-proxy` ahead of `bodyParser`.

People who have already run the proxy generator probably need to be
warned that they won't benefit from this bugfix.
Merge pull request #2568 from ef4/proxy-fix

Prevent mangled POST bodies in http-proxy
adding an addon postprocess hook for all javascript
extensible whitelist filters
Add --silent option for quieter UI

Passing the --silent command to any command will supress all output from
the UI expect errors.

Introduces write levels to the UI object. Changes pleasant-progress
commands to pass through the UI object first.  The UI simply delegates
the commands to it’s `PleasantProgress` object.
Merge pull request #2505 from ef4/ember-browserify

Automated npm/browserify/cjs loader
Merge pull request #2574 from chenn/master

Add --silent option for a quieter UI
added options alias processing to command model