[auth] Add custom icon for DreamHost (#4381)

This is my first PR for this repo; please let me know if I've done
anything incorrectly. I've got a couple other icons to submit if this
one looks good.

auth/assets/custom-icons/_data/custom-icons.json

@@ -269,6 +269,10 @@
     {
       "title": "Dropbox"
     },
+    {
+      "title": "DreamHost Panel",
+      "slug": "dreamhost_panel"
+    },
     {
       "title": "dus.net",
       "slug": "dusnet"

auth/assets/custom-icons/icons/dreamhost_panel.svg

@@ -0,0 +1,14 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!-- Generator: Adobe Illustrator 15.1.0, SVG Export Plug-In . SVG Version: 6.00 Build 0)  -->
+<!DOCTYPE svg PUBLIC "-//W3C//DTD SVG 1.1//EN" "http://www.w3.org/Graphics/SVG/1.1/DTD/svg11.dtd">
+<svg version="1.1" id="Layer_1" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" x="0px" y="0px"
+	 width="160.5px" height="160.5px" viewBox="0 0 160.5 160.5" enable-background="new 0 0 160.5 160.5" xml:space="preserve">
+<g>
+	<path d="M145.794,113.854c-11.111,5.932-23.811,9.227-37.417,9.008c-40.366-0.879-72.114-32.293-71.434-70.515
+		c0.227-12.961,4.309-25.042,11.112-35.148C26.512,28.841,11.771,50.589,11.318,75.851c-0.907,38.002,31.068,69.636,71.208,70.515
+		C109.284,146.805,132.642,133.844,145.794,113.854z"/>
+	<path fill="#0073EC" d="M86.833,14.123c-10.885,0-21.09,2.636-30.161,7.469c-5.669,9.007-8.844,19.331-9.297,29.875
+		c-0.68,33.171,27.212,60.63,61.909,61.289c10.432,0,22.224-2.417,31.294-7.249c5.443-9.007,8.617-19.551,8.617-30.754
+		C149.648,41.362,121.53,14.123,86.833,14.123z"/>
+</g>
+</svg>