V6 angular

[Elorfin]

These features are now managed by Angular JS :

• Summary of the Exercise when you open it
• Publish / Unpublish are done by AJAX calls
• List of Questions/Steps
• Edit of the metadata of the Exercise

Additionnal features :

• Add a step to an Exercise
• Remove a step from an Exercise
• Add an item to a Step (the creation of the Question is done in the old PHP form)
• Remove an item from a Step

Restored features :

• When Exercise has never been published the "Delete all papers" has been restored (in AJAX)