Auto-select paste URL

When creating a paste, we auto-select the resulting URL so that the user
only has to press CTRL+C to copy the link.
So you basically click "SEND" then press CTRL+C.

(cherry picked from commit 3feb4641c7892eeeaff2fe61c6e153919687b9c6)

Conflicts:
	css/zerobin.css

css/zerobin.css

@@ -111,12 +111,14 @@ h3 {
 
 #pasteresult a { color: #fff; }
 
-#pasteresult button { margin-left: 11px }
+#pasteresult button { margin-left: 11px; }
 
 #deletelink { float: right; }
 
 #toolbar, #status { margin-bottom: 5px; }
 
+#copyhint { color: #666; font-size: 0.85em; }
+
 button, .button, #expiration, #language {
 	color: #fff;
 	background-color: #323b47;
@@ -374,4 +376,4 @@ img.vizhash {
 	position: relative;
 	top: 2px;
 	left: -3px;
-}
+}