Use versions for dependencies

Using `dev-master` in `composer.json` can lead to some nasty dependency conflicts when using it in projects without `"minimum-stability": "dev"`. This change also syncs the dependencies with the `bower.json` file.

A tagged release after the merge would be appreciated. :wink: 
No problem, I'm happy Composer support exists!

`~3.0` means `>=3.0,<4.0`, so similar to `3.x.x`… :wink:

[Composer Package Versions](https://getcomposer.org/doc/01-basic-usage.md#package-versions)