Do tests before swapping the floating IP

It's always better to make sure there's no issue with the newly built image. Running a set of test on an instance that starts with the newly built image, only delete the old instance when it passes all of the tests.

Since we are having an intermittent problem with shibboleth, I will start with the shibd status checking as our first test.

Frameworks like Selenium might be used in the future for website tests.