Allow the destination directory for sync'ing assets to be configurable
Originally from this comment about using this with Thunder:
https://www.mydropwizard.com/comment/1273#comment-1273
Currently, we always set the destination to be './web/libraries/civicrm' but we should allow the user to configure that.
Perhaps we can look at the 'installer-paths' and try to figure out where the site usually puts it's libraries? Or, just have a special configuration parameter under 'civicrm' (like the extensions currently)?