Allow non-admin users to publish books

I've used the following test plan to check if the rights behave properly :

• Start from a blank instance
• Create 1 user "User" with no particular rights
• Install Book Versions API on the main wiki
• *Verify that the Publication right is properly registered on the main wiki* ; do not assign the right to anybody
• Create a sub-wiki
• Install Book Versions UI on the sub-wiki
• *Verify that the Publication right is properly registered on the sub wiki* ; do not assign the right to anybody
• Create one book with the admin
• Create a publication configuration where the book is published in a space of the main wiki
• *Verify that the admin can publish the book (the admin has programming rights)*
• *Verify that the user cannot publish the book*
• Add publish rights to the user on the book space
• *Verify that the user cannot publish the book (he still doesn't have rights on the target space)*
• Add publish rights to the user on the target wiki (checking a bit of inheritance)
• *Verify that the user can publish the book*
• Restart the instance
• Initialize the main wiki
• *Verify that the publish right still displays properly in the main wiki*
• Initialize the sub-wiki
• *Verify that the publish right still displays properly in the sub-wiki*
• *Verify that the user can still publish the book*
• Build the extension in a new (higher) version : mvn versions:set -DnewVersion=2.0-SNAPSHOT -DgenerateBackupPOMs=false
• Upgrade the API module on the main wiki
• *Verify that the publish right still displays properly in the main wiki*
• Upgrade the UI module on the sub-wiki
• *Verify that the publish right still displays properly in the sub-wiki*
• Drop publication right on the main wiki to the User
• *Verify that the user cannot publish the book (he doesn't have rights on the target space)*