PLT-1378 Initial version of emoji reactions (#4520)

* Refactored emoji.json to support multiple aliases and emoji categories

* Added custom category to emoji.jsx and stabilized all fields

* Removed conflicting aliases for :mattermost: and :ca:

* fixup after store changes

* Added emoji reactions

* Removed reactions for an emoji when that emoji is deleted

* Fixed incorrect test case

* Renamed ReactionList to ReactionListView

* Fixed 👍 and 👎 not showing up as possible reactions

* Removed text emoticons from emoji reaction autocomplete

* Changed emoji reactions to be sorted by the order that they were first created

* Set a maximum number of listeners for the ReactionStore

* Removed unused code from Textbox component

* Fixed reaction permissions

* Changed error code when trying to modify reactions for another user

* Fixed merge conflicts

* Properly applied theme colours to reactions

* Fixed ESLint and gofmt errors

* Fixed ReactionListContainer to properly update when its post prop changes

* Removed unnecessary escape characters from reaction regexes

* Shared reaction message pattern between CreatePost and CreateComment

* Removed an unnecessary select query when saving a reaction

* Changed reactions route to be under /reactions

* Fixed copyright dates on newly added files

* Removed debug code that prevented all unit tests from being ran

* Cleaned up unnecessary code for reactions

* Renamed ReactionStore.List to ReactionStore.GetForPost

webapp/tests/client_reaction.test.jsx

@@ -0,0 +1,81 @@
+// Copyright (c) 2016 Mattermost, Inc. All Rights Reserved.
+// See License.txt for license information.
+
+import TestHelper from './test_helper.jsx';
+
+describe('Client.Reaction', function() {
+    this.timeout(100000);
+
+    it('saveListReaction', function(done) {
+        TestHelper.initBasic(() => {
+            const channelId = TestHelper.basicChannel().id;
+            const postId = TestHelper.basicPost().id;
+
+            const reaction = {
+                post_id: postId,
+                user_id: TestHelper.basicUser().id,
+                emoji_name: 'upside_down_face'
+            };
+
+            TestHelper.basicClient().saveReaction(
+                channelId,
+                reaction,
+                function() {
+                    TestHelper.basicClient().listReactions(
+                        channelId,
+                        postId,
+                        function(reactions) {
+                            if (reactions.length === 1 &&
+                                reactions[0].post_id === reaction.post_id &&
+                                reactions[0].user_id === reaction.user_id &&
+                                reactions[0].emoji_name === reaction.emoji_name) {
+                                done();
+                            } else {
+                                done(new Error('test reaction wasn\'t returned'));
+                            }
+                        },
+                        function(err) {
+                            done(new Error(err.message));
+                        }
+                    );
+                },
+                function(err) {
+                    done(new Error(err.message));
+                }
+            );
+        });
+    });
+
+    it('deleteReaction', function(done) {
+        TestHelper.initBasic(() => {
+            const channelId = TestHelper.basicChannel().id;
+            const postId = TestHelper.basicPost().id;
+
+            const reaction = {
+                post_id: postId,
+                user_id: TestHelper.basicUser().id,
+                emoji_name: 'upside_down_face'
+            };
+
+            TestHelper.basicClient().saveReaction(
+                channelId,
+                reaction,
+                function() {
+                    TestHelper.basicClient().deleteReaction(
+                        channelId,
+                        reaction,
+                        function() {
+                            done();
+                        },
+                        function(err) {
+                            done(new Error(err.message));
+                        }
+                    );
+                },
+                function(err) {
+                    done(new Error(err.message));
+                }
+            );
+        });
+    });
+});