#127 `orderNb` column for the `validation_stamp` table
#127 Using the `orderNb` column for sorting
#127 Correct ordering on creation
#127 Added the 'orderNb' property on the 'ValidationStampSummary'
#127 Displays the `orderNb` property
#127 Takes the opportunity of cleaning the layout for the "Manage promotion levels" button
#127 Up/down arrows
#127 Up/down AJAX calls
#127 Up/down service layer