Move $scope.$watch site update to core

[egpbos]

For issue #42 we need the $scope.$watch in minimap/minimap.controller.js that is watching the filtered sites list to be moved to core. We need that $watcher to call an updating function for both the minimap site-footprints as well as the highlighted SiteBoxes from issue #42. In any case, it may make more sense to put it there, since sites are a core feature, and the sites.service is there as well.