verification of content-type and status code for http file server exercise

[jpdamon]

Clarified that setting the content-type and status code are now required. Added verification to exercise.js
Fixes #348

[martinheidegger]

Continuing conversation here:

Yes, the tests obviously didn't cover this particular use-case before so it would be good to have a test-case covering this particular problem. The test cases are quite simple: Just add a valid_0x.js file to the test/http_file_server/ folder that - without your fix - would have failed. You then can run the tests again using npm test.

Also it would be good if the PR would contain the locales in all languages - even if they are in english - since there is no fallback yet.

[jpdamon]

Makes sense, will do.

The issue I'm having though is that learnyounode verify still passes even when an error is emitted. How do I actually trigger a failure? This is my first contribution to this project so I apologize if this is answered somewhere else.

[martinheidegger]

😱 I only read the first part of your last comment. .emit('fail', ...) should work but currently doesn't - this is sort of okay - I need to fix this at a different levels of learnyounode and workshopper-adventure at more places than this. I plan to fix this all in one bunch (since it requires some restructuring) but here is the workshopper bug: workshopper/workshopper-adventure#81

[shanmukhateja]

This PR seems to be okay to be merged. Although its 2 years old, we could have somebody take a look at this.