1. added jobName for description
2. replace packageId with packages. This parameter is still type
   of string. But using white space to split the content for
   operating multipackages at once.
3. replace Job.PackageId (string) with Job.Packages (array of string)

this changes can be done task like this:
1. someone invoke InstallPackages("中文语言包", "foo-zh bar-zh")
2. lastore-session-helper will show "安装中文语言包成功" or "失败"
   using org.freedesktop.Notifications

Change-Id: I19f8cbe13907f49f0bedeab773d8b1ec6e9596f2