(MAINT) fix broken spec test

- fix broken spec test
- add check for deprecation warnings during spec testing
Merge pull request #541 from anodelman/maint

(MAINT) fix broken spec test
(QENG-437) beaker: EOL 1.8 ruby

- remove code chunks built for ruby 1.8
- update rspec + minitest, remove test/unit
- update spec tests to meet current rspec standard, here's a good
  reference
  http://teaisaweso.me/blog/2013/05/27/rspecs-new-message-expectation-syntax/