Chore/convert to typescript (#60)

* Convert to using TypeScript

Next.js v.9 allows converting an existing project to TS by simply renaming the files as TS files

* Fix type errors: Type 'string' is not assignable to type 'number'.

* Add mention about missing typings for javascript-time-ago

* Add GA_INITIALIZED to window

* Fix type error in feed transformers

* Model MembershipInfoForm state and props with TS

* Silence the typescript warning in MembershipInfoForm

* Add threshold to Fader props

* Fix Warning: Each child in a list should have a unique "key" prop.

Sponsors don't have ids – name is probably unique and can be used as a key

* Allow key as prop for SponsorLink

* Add type of the props for SponsorLink

components/Members.tsx

@@ -0,0 +1,43 @@
+import React from "react";
+import request from "axios";
+import shuffle from "lodash/shuffle";
+import api from "./api";
+
+export default class Members extends React.Component {
+  state = {
+    members: [],
+  };
+
+  componentDidMount() {
+    this.refreshMembers();
+  }
+
+  async refreshMembers() {
+    const res = await request.get(api("members"));
+    this.setState({
+      members: shuffle(res.data),
+    });
+  }
+
+  render() {
+    const members = this.state.members.map(member => {
+      const src = `${member.avatar_url}&s=120`;
+      return (
+        <img className="member" key={member.avatar_url} src={src} alt="" />
+      );
+    });
+
+    return (
+      <div className="members" aria-hidden="true">
+        <a
+          href="https://github.com/koodiklinikka"
+          target="_blank"
+          rel="noopener noreferrer"
+          tabIndex={-1}
+        >
+          {members}
+        </a>
+      </div>
+    );
+  }
+}