Issue #940706 by hanoii: added requirement for the libraries module to be enabled to prevent fatal error

added hook_perm implementation for viewing the beacon data; added script version field to the data stored by the beacon

changed so that boomerang still gets initialized but doesn't fetch images or contact beacon on excluded pages

added boomerang-plugin drush command to download plugin (largely based on a similar command in the Colorbox module); adding file this time