MUMUP-1209: Suppress Add to Home and Launch buttons when user doesn't have access

A number of things added to improve the user experience:
- When you don't have access, the buttons are grayed out and the cursor changes to a default cursor
- The buttons are no longer functioning links, and won't go anywhere when the user doesn't have access
- A popover appears if the user hovers over the button for more than a half second, saying "You do not have access to this app" (suggestions for better text welcome)

ex.
![image](https://cloud.githubusercontent.com/assets/1919535/4652134/2f803c82-54a2-11e4-9e75-21ad267b9454.png)

Everything still the same when you do have access, as expected:

![image](https://cloud.githubusercontent.com/assets/1919535/4652176/b063ef24-54a2-11e4-8b1c-4bd94bf24a88.png)

Are you mentioning other github users?