Add a confirmation HUD after uploading a page or post

This PR fixes: https://github.com/wordpress-mobile/WordPress-iOS-Editor/issues/406

After a user publishes/saves/schedules a post/page, they are presented with a confirmation HUD letting them know it's all good:

![scaled screen shot 2014-12-02 at 7 21 25 pm](https://cloud.githubusercontent.com/assets/154014/5288696/dc4a5418-7afc-11e4-962f-d549835f98b8.png)

or not:

![scaled screen shot 2014-12-03 at 2 50 54 pm](https://cloud.githubusercontent.com/assets/154014/5288689/c44caaa0-7afc-11e4-9385-f73df3bde613.png)

Note that the text in the HUD changes depending on what they are doing (publish/save/schedule). 

In order to style the HUD, I needed to update ```SVProgressHUD ``` to the latest version. Unfortunately, its author is not a fan of cocoapods and recommends we point to head, which I did:

> I'm not a big fan of CocoaPods, so tend to not keep it updated. If you really want to use SVProgressHUD with CocoaPods, I suggest you use pod 'SVProgressHUD', :head to pull from the master branch directly. I'm usually careful about what I push there and is the version I use myself in all my projects.

(From: https://github.com/TransitApp/SVProgressHUD) 

/cc @diegoreymendez 

I will encapsulate this into ``isPublished``` method.