PLT-1527 Add a slash command to set yourself away (#3752)

* added handlers for slash commands

* added manual status persistance

* added tests

* removed extra debug output and comments

* rebase - fixing the PR

* making echo messages after slash commands ephemeral

api/command_online.go

@@ -0,0 +1,42 @@
+// Copyright (c) 2016 Mattermost, Inc. All Rights Reserved.
+// See License.txt for license information.
+
+package api
+
+import (
+	"github.com/mattermost/platform/model"
+)
+
+type OnlineProvider struct {
+}
+
+const (
+	CMD_ONLINE = "online"
+)
+
+func init() {
+	RegisterCommandProvider(&OnlineProvider{})
+}
+
+func (me *OnlineProvider) GetTrigger() string {
+	return CMD_ONLINE
+}
+
+func (me *OnlineProvider) GetCommand(c *Context) *model.Command {
+	return &model.Command{
+		Trigger:          CMD_ONLINE,
+		AutoComplete:     true,
+		AutoCompleteDesc: c.T("api.command_online.desc"),
+		DisplayName:      c.T("api.command_online.name"),
+	}
+}
+
+func (me *OnlineProvider) DoCommand(c *Context, channelId string, message string) *model.CommandResponse {
+	rmsg := c.T("api.command_online.success")
+	if len(message) > 0 {
+		rmsg = message + " " + rmsg
+	}
+	SetStatusOnline(c.Session.UserId, c.Session.Id, true)
+
+	return &model.CommandResponse{ResponseType: model.COMMAND_RESPONSE_TYPE_EPHEMERAL, Text: rmsg}
+}