[add #146] Add a share button in paper page

The share button opens a popup.
This popup contains the paper permission manager.
Add changelog
[#161] Add report issue and clone link in the configuration

Add two new optional configurations:
 - blue.client.issues-url: link to report issues
 - blue.client.clone-url: where the code can be found.

The client side configuration manager has been improve.
All configurations stored in AppConfig is now automatically available in the constant
config.