Added error class to rspec raise_error expectations

[carbonin]

This removes warnings of the form:

WARNING: Using the `raise_error` matcher without providing a specific error or message risks false 
positives, since `raise_error` will match when Ruby raises a `NoMethodError`, `NameError` or 
`ArgumentError`, potentially allowing the expectation to pass without even executing the method you 
are intending to call. Instead consider providing a specific error class or message. This message can 
be supressed by setting: `RSpec::Expectations.configuration.warn_about_potential_false_positives = 
false`.

[Fryguy]

👍

[bdunne]

This should be a RuntimeError

[miq-bot]

Checked commit carbonin@fc1686b with ruby 1.9.3, rubocop 0.34.2, and haml-lint 0.13.0
2 files checked, 0 offenses detected
Everything looks good. 🍪

[bdunne]

👍 Will merge when Green