Setting up a gulp based builder

A simple [gulp](http://gulpjs.com/) based builder which should match exactly the behavior of the previous Makefile. I went with gulp over grunt since I wanted to try it out but also because it's asynchronous and uses node streams so no need for temp files.

To use, start with
```
npm install
```
From there, if you've installed gulp globally, you can just use 
```
gulp
```
to do all the tasks.

If you haven't installed gulp globally, 
```
make
```
will run the local gulp installation.

This also introduces a watcher which you can start with 
```
make watch
```
or 
```
gulp watch
```
and it will rebuild when there are changes to appropriate css or js.