Fix salt-ssh handling of python os.execv

This fix addresses an issue where the ssh_py_shim.py file attempts to run arguments with multiple parameters stuffed into index 0 of ARGV. This results in an error similar to:

`Function state.pkg /tmp/.salt/salt_state.tgz test=None pkg_sum=6dec40943712befb30b8e200fe5465dc hash_type=md5 is not available`

This is because the command line is effectively (note the last parameter):
`python /tmp/.salt/salt-call --local -l debug -c /tmp/.salt -- 'state.pkg /tmp/.salt/salt_state.tgz test=None pkg_sum=6dec40943712befb30b8e200fe5465dc hash_type=md5'`