CLOUDSTACK-5248: Fixed creation of mount point when running as non root (cloud) user.
The systemvm iso file is copied only when a systemvm or router vm is to be started on
a host. The file gets copied to the secondary storage. The mount point used is the one
that has permissions for regular user to mount a share.
CLOUDSTACK-5275: The failure was because a secondary storage wasn't available when the
host was added. When a setup is done through wizard the hosts get added before the
secondary storage. CS was tying to copy yhe systemvm iso to secondary and it used to
fail if it wasn't available. Made a change to copy the iso only when a systemvm is
being started on a host.
CLOUDSTACK-5202: Made changes to clean up mount points on stop and start.

All the three are related fixes; so putting a fix in one commit.