Fixed strange test dependency bug.

While running the test suite after implementing Lotus#Mounter and using
it in the microservices test, I noticed an intermittent test failure.
Further inspection revealed the application_test.rb .inherited test was
instantiating Frontend::Application.new and Backend::Application.new;
when this happened before the microservices tests ran, my test
exercising the path helpers always failed. I suspect it has something to
do with configuration objects being attached to the
Frontend::Application and Backend::Application classes on instantiation,
and therefore existing before the microservices test. However, it seemed
more expedient to change the test (since the test doesn't depend on
Frontend and Backend specifically, just two Lotus::Application
subclasses), than hunt down the cause. It also means that the
.inherited test no longer relies on those two applications, which is a
minor benefit.