Code reformatted

Translated all the debugging text into English (for internationalisation)

Replaced all the try/catch clauses with throw signatures (gives the user more flexibility debugging their code the way they want)
Added some comments
Some minor changes
Delete .project

People don't have to have the same IDE config as yours
Delete .classpath

People don't have to have the same IDE config as yours
Book.java :: @Override toString
Connexion.java :: Added try-with-resource blocks
Merge pull request #1 from IamAyman/master

Some changes