code: function build_aliases_hash(aliases) {
    var hash={};
    _.each(aliases, function(a) {
      var m;
      if ( (m = a.match(/^([^.]+)\.(.+)$/)) ) {
        if (hash[m[1]])
          hash[m[1]].push(m[2]);
        else
          hash[m[1]] = [m[2]];
      }
    });
    
    return hash;
  }
docs: Given array of full alias names like "foo.bar", "foo.baz" build hash like {"foo" : ["bar", "baz"]}