(maint) refactor SettingsReader expectations

Prior to this commit, when given a settings file, the test would call
.expects multiple times, once for each line that was sent to the logger.
This commit refactors those calls to add .at_least_once instead of
calling .expects multiple times.
Merge pull request #189 from jeffweiss/dont_tell_me_about_defaults_twice

(maint) refactor SettingsReader expectations