Iconify public/private streams on subs page and new stream modal

This will hopefully make stream privacy more noticeable. We still don't
allow people to modify privacy after stream creation, however.

Since we now use a radio box on the stream creation modal we had to change
the selector used by subs.js to determine if a new stream was to be invite-
only.

(imported from commit 641a4fab74301a9b3ecd4b3859f010dd4ece193e)

templates/zephyr/stream_creation_prompt.html

@@ -7,9 +7,16 @@
   <form id="stream_creation_form" class="form-inline">
       <div class="modal-body">
           <div id="make-invite-only">
-            <label class="checkbox">
-              <input id="invite-only" type="checkbox" name="invite-only" />
-              Make stream invite-only
+            <b>Stream accessibility</b><br />
+            <label class="radio">
+              <input id="invite-only" type="radio" name="privacy" value="public" checked />
+              <span class="icon-globe"></span>
+              Anyone can join
+            </label><br />
+            <label class="radio">
+              <input id="invite-only" type="radio" name="privacy" value="invite-only" />
+              <span class="icon-lock"></span>
+              People must be invited
             </label>
           </div>
           <br />

zephyr/jstemplates/subscription.html

@@ -20,6 +20,10 @@
 
     <div id="subscription_settings_{{id}}" class="collapse subscription_settings">
       <div class="regular_subscription_settings collapse {{#subscribed}}in{{/subscribed}}">
+          <p>This is a
+          {{#if invite_only}}<span class="icon-lock"></span> <b>invite-only stream</b>. Only people who have been invited can access its content, but any member of the stream can invite others.
+          {{else}}<span class="icon-globe"></span> <b>public stream</b>. Anybody in your organization join.{{/if}}
+          </p>
         <span class="sub_settings_title">Settings</span>
         <ul>
           <li><div class="sub_setting_show_in_home">

zephyr/static/js/subs.js

@@ -663,7 +663,10 @@ $(function () {
         });
         // You are always subscribed to streams you create.
         principals.push(email);
-        ajaxSubscribeForCreation(stream, principals, $('#invite-only').is(':checked'));
+        ajaxSubscribeForCreation(stream,
+            principals,
+            $('#stream_creation_form input[name=privacy]:checked').val() === "invite-only"
+            );
     });
 
     $("#subscriptions_table").on("click", ".sub_unsub_button", function (e) {