Acknowledging contributions

I've installed the [allcontributors bot](https://allcontributors.org/) to acknowledge contributions to this repository. Here is how to invoke it:

```
@all-contributors please add for
```

It can recognize the following contribution types:

Emoji/Type | Represents | Comments
-- | -- | --
🔊 audio | Audio | Podcasts, background music or sound effects
♿️ a11y | Accessibility | Reporting or working on accessibility issues
🐛 bug | Bug reports | links to issues reported by the user on this project
📝 blog | Blogposts | links to the blogpost
💼 business | Business Development | people who execute on the business end
💻 code | Code | links to commits by the user on this project
🖋 content | Content | e.g. website copy, blog posts are separate
🔣 data | Data | links to contributed data for the project (both tests and datasets)
📖 doc | Documentation | links to commits by the user on this project, Wiki, or other source of documentation
🎨 design | Design | links to the logo/iconography/visual design/etc.
💡 example | Examples | links to the examples
📋 eventOrganizing | Event Organizers | links to event page
💵 financial | Financial Support | people or orgs who provide financial support, links to relevant page
🔍 fundingFinding | Funding/Grant Finders | people who help find financial support
🤔 ideas | Ideas & Planning |  
🚇 infra | Infrastructure | Hosting, Build-Tools, etc. Links to source file (like travis.yml) in repo, if applicable
🚧 maintenance | Maintenance | people who help in maintaining the repo, links to commits by the user on this project
📦 platform | Packaging | porting to support a new platform
🔌 plugin | Plugin/utility libraries | links to the repo home
📆 projectManagement | Project Management |  
💬 question | Answering Questions | Answering Questions in Issues, Stack Overflow, Gitter, Slack, etc.
👀 review | Reviewed Pull Requests |  
🛡️ security | Security | identify and/or reduce security threats, GDPR, Privacy, etc
🔧 tool | Tools | links to the repo home
🌍 translation | Translation | links to the translated content
⚠️ test | Tests | links to commits by the user on this project
✅ tutorial | Tutorials | links to the tutorial
📢 talk | Talks | links to the slides/recording/repo/etc
📓 userTesting | User Testing | links to user test notes
📹 video | Videos | links to the video

Using the bot is contingent on a PR like #70 that creates a markdown file to place contributor information into. Once we have this, I'll give the bot a go.