Closes browser after every scenario
Closes browser after every scenario

Without this, selenium webdriver continues to use an existing
browser instance from prior scenario when multiple scenarios are
being run together.

This is non-ideal because some assertions will fail, especially
login related assertions throw this error:
```error
spec/spec_support/cas_login.rb:57:in `complete_login'"	message: "Unable to find visible field \"username\" that is not disabled"
```

This happens because the scenario is attempting a fresh login, but
gets to an already logged in page from prior session.

ndlib/QA_tests,ndlib/QA_tests,ndlib/QA_tests