Bug #3914 : removing of boring JavaScript message alerts when logging to Silverpeas (under Chrome only).

- preventing from getting conflicts between jQuery plugin and another javascript plugin
- removing some dead code
- removing calls of javascript plugins that don't exist

The reason of getting JavaScript message alerts, the ones that are now removed, still exists. But instead of displaying the error with JavaScript message alert, the error is logged into the log console of the Web browser.
The origin of the error is very hard to explain because of frameset use (that is sometimes inducing, but not always, some frame reloading) and because of several ajax requests performed when arriving to Silverpeas's homepage from login page.