Make manager specs a little clearer

… by getting rid of subject
Refactored duplicated code in manager base spec
Refactor similar code in redis_registry_base_spec
Refactor a little more similar spec code
Use singleton class instead of global variable

I really must switch these tests to rspec. Minitest is really chapping
my arse.
Don't use class variables
Avoid using {} for multi-line blocks
Spaces missing after comma
Finish the last few stylistic fixes
Merge pull request #6 from wideopenspaces/implement_pull_review_suggestions

Implement pull review suggestions