Improvements to the Rake task config (for tests)

* Refactor the commmon config options
* Some other prettification
Make the "App" more robust to invalid params.

Specifically, check for a valid logger being passed in. (Quack!)
Make server e2e test more robust.

Earlier, we would wait 3s till we start the tests, which was sufficient
time for the server to have started. However, with recent changes in the
Runner code, the app always runs with a proper File causing startup times
to be slower and tests to fail. We now wait longer.
Get rid of useless test_helper file.

Its only purpose was to load the main project (and some libs). Now,
the project is loaded as part of rspec config and the libs are loaded
by whichever test files need them.