Move button to its own component

fix css linting errors

src/components/RsvpButton/RsvpButton.css

@@ -76,32 +76,6 @@
   opacity: 0.9;
 }
 
-.button {
-  display: block;
-  box-sizing: border-box;
-  margin: 0;
-  padding: 10px 16px;
-  width: 100%;
-  opacity: 0.75;
-  outline: 0;
-  border: 4px solid #fff;
-  border-radius: 14px;
-  background: var(--colour-nearblack);
-  color: #fff;
-  text-align: center;
-  text-decoration: none;
-  font-size: 18px;
-  line-height: 1.3333333;
-  cursor: pointer;
-  transition: opacity ease-in-out 0.25s, box-shadow ease-in-out 0.25s;
-}
-
-.button:hover,
-.button:focus {
-  opacity: 0.9;
-  box-shadow: 0 0 4px #fff;
-}
-
 @keyframes shake {
   8%,
   41% {

src/components/RsvpButton/RsvpButton.js

@@ -2,6 +2,7 @@ import React, { PropTypes } from 'react';
 import withStyles from 'isomorphic-style-loader/lib/withStyles';
 import s from './RsvpButton.css';
 import fetch from '../../core/fetch';
+import Button from '../Button';
 
 class RsvpButton extends React.Component {
   static propTypes = {
@@ -79,9 +80,9 @@ class RsvpButton extends React.Component {
             !this.state.showRsvpForm ? s.rsvpVisible : null,
           ].join(' ')}
         >
-          <button className={s.button} onClick={this.showRsvpForm}>
+          <Button onClick={this.showRsvpForm}>
             RSVP
-          </button>
+          </Button>
         </div>
         <div
           className={[