Move chat to slack (#477)

This closes #201. 🎉

CONTRIBUTING.md

@@ -12,7 +12,7 @@ You could:
 - [Build new features][build-new-features]
 - [Help triage issues][help-triage-issues]
 
-Not sure where to start? Join us [on gitter](https://gitter.im/redfin/react-server) and ask!
+Not sure where to start? Join us [on slack](https://slack.react-server.io/) and ask!
 
 ## Getting started
 

README.md

@@ -3,7 +3,7 @@
 [![Build Status][build-badge-img]][build-url]
 [![NPM version][npm-version-img]][npm-url]
 [![NPM downloads per month][npm-downloads-img]][npm-url]
-[![Chat on Gitter][gitter-img]][gitter-url]
+[![Chat on Slack][slack-img]][slack-url]
 [![NPM license][npm-license-img]][npm-url]
 [![Powered by Redfin][redfin-img]][redfin-url]
 
@@ -81,5 +81,5 @@ See [the contributing guide](CONTRIBUTING.md) to get started.
 [npm-version-img]: https://badge.fury.io/js/react-server.svg
 [npm-license-img]: https://img.shields.io/npm/l/react-server.svg
 [npm-downloads-img]: https://img.shields.io/npm/dm/react-server.svg
-[gitter-url]: https://gitter.im/redfin/react-server?utm_source=badge&utm_medium=badge&utm_campaign=pr-badge&utm_content=badge
-[gitter-img]: https://badges.gitter.im/redfin/react-server.svg
+[slack-url]: https://slack.react-server.io/
+[slack-img]: https://slack.react-server.io/badge.svg

docs/README.md

@@ -6,7 +6,7 @@ bring-your-own Flux implementation stack.  At Redfin, we use
 [Spring MVC](http://docs.spring.io/spring/docs/current/spring-framework-reference/html/mvc.html)
 and [Reflux](https://github.com/reflux/refluxjs), respectively, but it shouldn't
 matter what technology you chose for either.  Choosing a tech stack is out of
-scope for our documentation, but come swing by our gitter if you'd like to talk
+scope for our documentation, but come swing by our [slack](https://slack.react-server.io/) if you'd like to talk
 about it.
 
 If you still aren't convinced on React Server, check out our