Add Content-* headers for empty POST requests

[dd32]

Sends the Content-Length and Content-Type headers even for empty POST requests.

The test passes regardless, as it seems that the Heroku test app adds the Content-Length headers on incoming requests regardless of if it's sent. Testing against http://httpbin.org/post shows that the header isn't/is sent though.

Fixes #248

[jrfnl]

@dd32 Thank you for this PR and sorry for the long wait.

The change make sense to me.

Looks like #318 also addresses this. Would it be beneficial to add the unit tests from #318 into this PR ? or combine them in some way ?

Also, the assertEquals() should probably be changed to an assertSame() ?

Other than that, would you mind rebasing the PR so it becomes mergable ?
If you don't want to or don't have the time, please let me know.

[dd32]

I'm unable to rebase this as I no longer have the original repository it was made in.

It looks like a new PR combining this & #318 would make sense (I don't have the bandwidth for this right now)

[jrfnl]

@dd32 Thanks for letting me know. I've created PR #368 now which consolidates both previous PRs. Feedback welcome.