[imp] Improve register page design

Add input label, change order of buttons, add a text indication for required input
Clear cache on logout

Clear the cache when an user logout. A new service is added to clear the cache.
[imp] Improve long polling compiler sumbscription

Now previews and data are only updated when successful compilation
[new] Option to delete synchronised file

Add a service to delete a synchronised file based on the mobwrite protocol
[new] Clicking on a resource, insert it in the text
[fix] Fix paper preview resize

Fix the display of the preview when the scalling fator is not set to auto. And the current line is now correcly highlight when the scala factor change
[new] Dipslay paper compiler options

Display compiler options on paper page
[fix] Fix parse of the response of get copilers

Angularjs doesn't parse correcly array of string, the response is persed manualy