changes to beaker RSpec spec test best practices.

[Alice Nodelman]

With the coming EOL of ruby 1.8 support we are upgrading our RSpec support to latest.  This means that we will also be adopting latest RSpec method names.

The main changes will be in the removal of 'should' and 'stub' statements, which will now be 'expect' and 'allow'.

For a rundown see:

http://teaisaweso.me/blog/2013/05/27/rspecs-new-message-expectation-syntax/

(yes, this is from 2013, that's how far behind we are)

I am adding a check in Beaker smoketests to fail on RSpec deprecation warnings - we will no longer support the old format.

Thanks!

alice.