Update logout to rescue exception if session has expired
Update logout to rescue exception if session has expired

- Occasionally CI would fail during teardown when the client would
  attempt to logout after the session had expired
- We now rescue this exception and continue

[#112196689](https://www.pivotaltracker.com/story/show/112196689)

Signed-off-by: Lyle Franklin <31e283733c7a4b3b6cb03b95ab535671c2112bbe@pivotal.io>

cloudfoundry-incubator/bosh-vsphere-cpi-release,cloudfoundry-incubator/bosh-vsphere-cpi-release,cloudfoundry-incubator/bosh-vsphere-cpi-release,cloudfoundry-incubator/bosh-vsphere-cpi-release,cloudfoundry-incubator/bosh-vsphere-cpi-release