Now that rack is locked to > 1.6.2, we don't need all of this custom
logic in the builder initializer. Using a memoizer we can remove the
initial @options set.
The settings tests were causing tests in other files to fail
depending on the order they were run in. We'll reset the config
values after each expectation.
For some reason coveralls has decided that various changes in the
gemspec and Gemfile have decreased code coverage by .1%, so let's
go overboard and add a bunch of coverage for the builder.
