Refs #2327

 * Tested & fixed behavior for bad use cases: wrong piwik server, apache shutdown, mysql shutdown
 * Now exceptions thrown during init() (DB connection errors etc) are thrown properly from piwik when piwik files used internally and where PIWIK_ENABLE_DISPATCH is off 
 * Now authorizing archiving requests from this archive.php script, when "browser triggered archiving" is disabled, these http requests still will work (when super user authenticated + using &trigger=archivephp in http request as flag)
 * added help option which displays the doc
 * Ensures that script can only be executed from CLI  

TODO
 * Check error handling in cron 
 * Fix bug when initial run of the day and ignores inactive websites
 * Add sample output link

git-svn-id: http://dev.piwik.org/svn/trunk@5090 59fd770c-687e-43c8-a1e3-f5a4ff64c105