function handlePostUserRequests(oXhr) {
		var oUser,
			sResponseBody;

		oUser = getUserDataFromRequestBody(oXhr.requestBody);

		// Check if that user already exists
		if (isUnique(oUser.UserName)) {
			aUsers.push(oUser);

			sResponseBody = '{"@odata.context": "' + getBaseUrl(oXhr.url)
				+ '$metadata#People/$entity",';
			sResponseBody += JSON.stringify(oUser).slice(1);

			// The response to POST requests is HTTP 201 (Created)
			return [
				201,
				{
					"Content-Type" : "application/json; odata.metadata=minimal",
					"OData-Version" : "4.0"
				},
				sResponseBody
			];
		}
		// Error
		sResponseBody = duplicateKeyError(oUser.UserName);
		return [
			400,
			{
				"Content-Type" : "application/json; charset=utf-8"
			},
			sResponseBody
		];
	}
Handles POST requests for users and returns a fitting response.
Creates a new user according to the request.
Does NOT check for duplicate user names because that is how the live service behaves.
@param {Object} oXhr - the Sinon fake XMLHttpRequest
@returns {Array} an array with the response information needed by Sinon's respond() function