OO-1042: check the boundaries of the hibernate bag before add a checkpoint, clean the velocity container and reload all data after a save...

OO-1038: better check of long without exception, try and catch in PersistingCourseGroupManager, unit tests

-no-jira: replace escaping with antisamy for group description as the description is edited with TinyMCE (which already escape special characters)

OO-716: replace the flot library in the course statistics with the bar chart component which use d3.js

OO-1014: give the right name to identify the type of image in the repository details, fix the "grayed tone all pictures"!

OO-1015: don't log NoSuchFieldException while exporting a group, if the field don't exist, we want that it doesn't exist

OO-716: most charts are horizontal, add units everywhere, refactor to a factory to generate the content of charts for items...