Whitespace fixin
(maint) Finish incomplete config test

The updated test here was never finished. It set expectations without
invoking any methods. This commit fixes a bug about which namespace
would receive the git_sha_or_tag method and adds a method call to test
the behavior.
(maint) Use around to simplify teardown and setup

Using rspec's around syntax vastly simplifies teardown and setup in
tests that require setting and later resetting variables. This commit
updates several examples in the config spec to use this syntax.
Merge pull request #311 from haus/maint/master/spec_improvements

(maint) Spec improvements