CLOUDSTACK-2450: Fix userdata to be urlencoded safely

urlencoding the userdata and quoting the = since apiserver will strip
them out. This will send an invalid userdata down to the plugin (vmops)
where base64 decoding fails causing vm deployment to fail.

Signed-off-by: Prasanna Santhanam <tsp@apache.org>
(cherry picked from commit 0edd2a8e14482def0d2a73726b53dee4239e2822)