Better uploader directive

# What's New? / Why?

 * NgS3Upload wasn't really meeting out needs and was forcing us to write some hacks
 * I wrote a new uploader directive. Here's an example:
```html
<input type="file" uploader="fileUrl">
```
Where `$scope.fileUrl` will become the URL of the file as it is stored on AWS.

# What's Next?

 * Add images to everything (Users, stages, etc...)