article view improvements

> OK, I've tested it.
> Some remarks :
> - can you decrease the size of the title now displayed on the action bar, in order to show a little more text
> - I think you should keep the Mark as read button at the bottom, even though the other is practical
> - Can it be possible to have an icon for the new mark at read button, instead of this kind of menu ?

i've added back the button below the content. The upper one is now a button with an image (it's a system icon, we can change it, if we have a better one), see screenshot:
![checkmark](https://cloud.githubusercontent.com/assets/4399446/5460600/6b051eba-8564-11e4-97cc-76f75bd9627a.png)
  
I'll look at the first remark tomorrow, but it shouldn't be a big deal to decrease the font size.