environs/sshstorage: fix intermittent test failure

The initial "bash" command was changed at some
point from being all-on-the-command-line to bash
executing a script on stdin. The test changes to
reflect that.

Fixes https://bugs.launchpad.net/juju-core/+bug/1323898
Merge pull request #11 from axw/sshstorage-test-failure

The initial "bash" command was changed at some point from being all-on-the-command-line to bash executing a script on stdin. The test changes to reflect that.

Fixes https://bugs.launchpad.net/juju-core/+bug/1323898