bug #4737 :  Add a whitelist of files that can be uploaded. The whitelist is based upon the file extension.
bug #4737 :  The whilelist is now based upon the mime-type of the files in order to avoid the wrong file extension. Browses also the files in directories while uploading a zip website archive

Conflicts:

	websites/websites-config/src/main/config/properties/org/silverpeas/webSites/settings/webSiteSettings.properties
bug #4737 :  When updating a page name, the extension of the file isn't taken into account and it is added to the updated file name