icons: Clean up refresh.svg

Remove metadata and clean up the SVG tags to make it simpler.

src/default-theme/icons/md/refresh.svg

@@ -1,11 +1,6 @@
 <?xml version="1.0" encoding="utf-8"?>
-<!-- Generator: Adobe Illustrator 19.2.1, SVG Export Plug-In . SVG Version: 6.00 Build 0)  -->
-<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"
-	 viewBox="0 0 18 18" style="enable-background:new 0 0 18 18;" xml:space="preserve">
-<style type="text/css">
-	.st0{fill:none;}
-</style>
-<path d="M13.7,4.3C12.5,3.1,10.8,2.4,9,2.4c-3.6,0-6.6,3-6.6,6.6s2.9,6.6,6.6,6.6c3.1,0,5.6-2.1,6.4-5h-1.7
-	c-0.7,1.9-2.5,3.3-4.7,3.3c-2.7,0-5-2.2-5-4.9s2.2-4.9,5-4.9c1.4,0,2.6,0.6,3.5,1.5L9.8,8.2h5.8V2.4L13.7,4.3z"/>
-<path class="st0" d="M0,0h18v18H0V0z"/>
+<svg version="1.1" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" viewBox="0 0 18 18">
+    <path d="M13.7,4.3C12.5,3.1,10.8,2.4,9,2.4c-3.6,0-6.6,3-6.6,6.6s2.9,6.6,6.6,6.6c3.1,0,5.6-2.1,6.4-5h-1.7
+        c-0.7,1.9-2.5,3.3-4.7,3.3c-2.7,0-5-2.2-5-4.9s2.2-4.9,5-4.9c1.4,0,2.6,0.6,3.5,1.5L9.8,8.2h5.8V2.4L13.7,4.3z"/>
+    <path fill="none" d="M0,0h18v18H0V0z"/>
 </svg>