Weirdness in tests

[subnetmarco]

This is an interesting problem that I noticed. When running tests locally with busted -o spec/busted-print.lua --coverage spec/ spec/ two things happen:

• The same tests are executed more than once. Here is my log: https://gist.github.com/thefosk/7fa5c1e92f637810acf2 (for example search for admin_api_spec.lua, it appears two times)
• Some tests are not being executed at all, for example plugins_configurations_routes.lua (you can see it from my same log).

I noticed the same problem on Travis (for example at https://travis-ci.org/Mashape/kong/builds/65202359).

[thibaultcha]

• It runs twice because the right command is busted -o spec/busted-print.lua --coverage spec/.
• It doesn't run because it doesn't have the _spec suffix.