uninstall_plugins: don't break on plugin missing (#670)
uninstall_plugins: don't break on plugin missing (#670)

It might be the case that the plugin was already deleted, because
we're uninstalling it from the whole system.
In this case, no need to try and update its state, it's gone.
Just ignore the 404 then.
cloudify-cosmo/cloudify-agent,cloudify-cosmo/cloudify-agent