Pull in Modified gulp-starter

Hello!

I thought this project could use some gulp love... so I pulled in @greypants [gulp-starter](https://github.com/greypants/gulp-starter), which is amazing, and sorted out some interesting problems getting it to work with angular which I have zero experience with. As a result, I've likely screwed up somewhere or failed to account for something so please let me know, and I'll can try to fix it.

This PR changes quite a few things. I don't expect it to get merged wholesale, and I'm happy to make any changes or fixes that are required.

I have [another branch](https://github.com/solomonhawk/angularjs-gulp-browserify-boilerplate/tree/gulp-refactor-rev-sass-bootstrap) that contains a bit more sass bootstrap stuff that you may or may not be interested in including in this repo. My thoughts are it's probably likely people will rip a lot of it out, but at the same time it provides a bit more of a jumping off point as far as folder/file structure goes and some helpful general styles. 

Some other thoughts:
* It would be neat to also include an html templating language like haml or jade, I know there's a browserify transform for haml (hamlify-js)
* Coffeescript would be a nice addition though it's not everyone's favorite flavor, there's also a browserify transform for that (coffeeify)

There are a couple of issues I've outlined in my comments below.
I'd personally prefer to avoid adding a ruby dependency. `gulp-ruby-sass` could very well be more stable/feature-rich, but I'd like to avoid the added complexity for this boilerplate.