Change Badge System to New Shields Badge

Related to Issue #361, which is how the current 'new' badge works (Or doesn't), and the fact that currently the badge is static and manually updated by the bot.

I have just had a PR approved into shields, which should make its way to production in the coming days, which adds an 'All Contributors' badge type. This is dynamically generated from the `.all-contributorsrc` file.

The Bade URL is as follows:

```
https://img.shields.io/github/all-contributors/owner/repo
```

It also supports specifying a branch for those that aren't using master as the default branch. I will update this issue once the badge hit's production.