Updates the iOS Wikitude SDK to version 3.3.1;

Signed-off-by: Andreas Schacherbauer <andreas.schacherbauer@wikitude.com>
Merge branch 'Integration_3_3_1' of github.com:Wikitude/wikitude-phonegap into Integration_3_3_1
Merge pull request #39 from AndreasSchacherbauerWikitude/Integration_3_3_1

Updates the iOS Wikitude Plugin to version 3.3.1