Updates Wikitude iOS SDK to version 4.0.2;

Signed-off-by: Andreas Schacherbauer <andreas.schacherbauer@wikitude.com>
Merge pull request #6 from AndreasSchacherbauerWikitude/Integration_4_0_3

Updates Wikitude iOS SDK to version 4.0.2;
Merge pull request #7 from Wikitude/Integration_4_0_3

Integrates the Wikitude iOS SDK 4.0.2 into the Wikitude Xamarin component.