Changes HttpResponse html(String) behaviour

[ChristianSteffens]

This PR makes two changes:

• Adds CHANGELOG.md and README.md to the Xcode-Project for easy access
• Changes the behaviour for HttpResponse case html: This case now needs a full html-string (not only the body-part). For compatibility reason we added a htmlBody case as well, that case will only need the body-part then.

We need to provide a full html-string (with a custom head section), unfortunately the existing html case in HttpResonse always provides a fix head-part (that is probably perfectly fine for most cases).

As this PR makes this version incompatible to previous ones in terms of the html response I would certainly understand any vetos. Then again the case is called html and not htmlBody so it is / might be misleading anyhow - so IMHO would recommend changing the behaviour as this PR provides.

[swifter-bot]

	2 Warnings
⚠️	It seems like you’ve added new tests to the library. If that’s the case, please update the XCTestManifests.swift file running in your terminal the command swift test --generate-linuxmain.
⚠️	If you ran the command swift test --generate-linuxmain in your terminal, please remove the line testCase(IOSafetyTests.__allTests__IOSafetyTests), from public func __allTests() -> [XCTestCaseEntry] in the bottom of the file. For more reference see #366.

	1 Message
📖	Hey, @ChristianSteffens 👋.

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[Vkt0r]

@ChristianSteffens Thanks for taking the time to create this PR! I think it makes sense to have the ability to provide a full HTML string and not the only the body as you mentioned. This change would break compatibility but I think it's really low compared with the advantage of having both options (body and full HTML).

Can you please update the DemoServer.swift to use the htmlBody instead of the html for the cases in which was used ?

[ChristianSteffens]

I updated the tests.

[Vkt0r]

@ChristianSteffens Thanks can you please rebase it and get rid of the conflict? I would happily merge it after that.

[ChristianSteffens]

Done.

[Vkt0r]

This looks good! Thanks.