Bug #4794 and #4766 : fixing Silvercrawler download and upload problems

- adding HTTP 403 error handling
- adding two common Silverpeas Http Servlet (one to verify the user is authenticated)
- adding common treatment to check that the access of a file is not relative
- wiring the ComponentRequestRouter with the new Silverpeas Http Servlet
- improving index management around repositories

Do not forget to check pull request on Silverpeas-Core...

Please to perform tests on a Server running on Windows and others on a Server running on Linux.