Merge branch '12743-subscribe-to-label' into 'master'

Allow subscribing to labels

This implement #12743 and supersedes !2799 (thanks @timothyandrew!).

- Subscribe (and unsubscribe) for labels
- When an issue/merge request is created, notify all subscribers of all its labels
- When an issue/merge request is edited, notify all subscribers of all its newly-added labels

## Done

- [x] Verify that a user is signed in to subscribe/unsubscribe from a label.
- [x] Merge conflicts
- [x] Integration tests
- [x] `issuable.subscribed?` should check subscribers and participants
- [x] When an issuable is relabeled, notify subscribers of the *newly added* labels only
- [x] Screenshots:

### Labels page

![Screen_Shot_2016-03-07_at_19.05.44](/uploads/3e69064e9e1a06ee2e27c778776c1407/Screen_Shot_2016-03-07_at_19.05.44.png)

### HTML email

![Screen_Shot_2016-03-07_at_19.07.36](/uploads/e484e06366a738385f1f6d71b52eecf7/Screen_Shot_2016-03-07_at_19.07.36.png)

### Plain text email

![Screen_Shot_2016-03-07_at_19.07.50](/uploads/dc05f710a8f7ab5eae9f72aa2110e741/Screen_Shot_2016-03-07_at_19.07.50.png)

PS: I've set the milestone to 8.6 since it's getting late for 8.5...

See merge request !3115

2 files changed, 23 insertions, 15 deletions

diff --git a/app/assets/javascripts/subscription.js.coffee b/app/assets/javascripts/subscription.js.coffee
index 7f41616d4e7..084f0e0dc65 100644
--- a/app/assets/javascripts/subscription.js.coffee
+++ b/app/assets/javascripts/subscription.js.coffee
@@ -1,17 +1,21 @@
 class @Subscription
-  constructor: (url) ->
-    $(".subscribe-button").unbind("click").click (event)=>
-      btn = $(event.currentTarget)
-      action = btn.find("span").text()
-      current_status = $(".subscription-status").attr("data-status")
-      btn.prop("disabled", true)
-      
-      $.post url, =>
-        btn.prop("disabled", false)
-        status = if current_status == "subscribed" then "unsubscribed" else "subscribed"
-        $(".subscription-status").attr("data-status", status)
-        action = if status == "subscribed" then "Unsubscribe" else "Subscribe"
-        btn.find("span").text(action)
-        $(".subscription-status>div").toggleClass("hidden")
+  constructor: (container) ->
+    $container = $(container)
+    @url = $container.attr('data-url')
+    @subscribe_button = $container.find('.subscribe-button')
+    @subscription_status = $container.find('.subscription-status')
+    @subscribe_button.unbind('click').click(@toggleSubscription)
 
-    
+  toggleSubscription: (event) =>
+    btn = $(event.currentTarget)
+    action = btn.find('span').text()
+    current_status = @subscription_status.attr('data-status')
+    btn.prop('disabled', true)
+
+    $.post @url, =>
+      btn.prop('disabled', false)
+      status = if current_status == 'subscribed' then 'unsubscribed' else 'subscribed'
+      @subscription_status.attr('data-status', status)
+      action = if status == 'subscribed' then 'Unsubscribe' else 'Subscribe'
+      btn.find('span').text(action)
+      @subscription_status.find('>div').toggleClass('hidden')
diff --git a/app/assets/stylesheets/pages/labels.scss b/app/assets/stylesheets/pages/labels.scss
index 5ec0966194c..61ee34b695e 100644
--- a/app/assets/stylesheets/pages/labels.scss
+++ b/app/assets/stylesheets/pages/labels.scss
@@ -41,3 +41,7 @@
 .color-label {
   padding: 3px 4px;
 }
+
+.label-subscription {
+  display: inline-block;
+}