* Update plugins/download-commands from branch 'master'
to 5bd359c08e10b93d2c08762f75cde01a14e45fc6
- use unqiue constants for each download command
Since these are used to record user preferences, make sure each one
is unique and we don't re-use existing ones.
Change-Id: I4cea0f1ac22d70db9211c05edd633dfb98713560