HTML5 flow elements, as well as a re-built all.js

Hey,

I took a stab at a couple things real quick. Not sure if this is "master-ready," but it didn't break any tests :+1: 

First of all, I was stumped why the tests I was running through the terminal were throwing errors that the browser test runner weren't. I tracked that down to `dist/all.js`, which seems to have been out of date with the source files. I didn't see a build process for generating/concatenating all.js, so I just copy and pasted in its parts, and voila, it worked.

Once I got that figured out, I created a new map in the parser for [HTML5 flow elements](https://developer.mozilla.org/en-US/docs/HTML/Content_categories#Flow_content), and updated the code to not pressure these elements to have only one type of content within them.

I added a couple tests for these flow elements, as well as a test for custom components, which seem to be working now that all.js is updated.

Let me know what you think. I'm happy to make adjustments or discuss further the best way to proceed with supporting these new flow elements and custom components.

[#46, https://github.com/yeoman/yeoman/issues/1010, https://github.com/yeoman/grunt-usemin/issues/87]