missing tests? (GH-25)

was: Dancer::Test & copy some pod from Dancer 1

Following up on https://github.com/PerlDancer/Dancer2/issues/25, I am looking into the missing tests. 

I believe that we want all Dancer 1 tests for compatibility reasons.

In it's initial version this PR provides only pod (99% copied from old Dancer). Will try to re-create the test functionality next.

PS: Updated PR. It seems we're missing only 'read_logs' and 'response_redirect_location_is' from Dancer 1