compile test package on each godog execution - in order to show custom formats as an example

Since after go 1.5 release compilation speed got worse, it made sense to prevent godog from compiling the test package on commands like `godog --help` or `godog --version`. But this will not show registered custom formatters, maybe it is worth to revisit it when go 1.8 is released

Start by reproducing the behavior with `godog --help` and `godog --version`, then trace how each command decides whether to compile the test package. Check how registered custom formatters are discovered and compare the startup cost before and after the change. Done means the commands can show custom formatters as examples without breaking their expected behavior.

Written by the indexing model from the issue text.