Update to PSPDFKit 7 for iOS

Merge pull request #29 from PSPDFKit/rad/update-to-pspdfkit7

Update to PSPDFKit 7

Update to PSPDFKit 3.3 for Android

Merge pull request #22 from PSPDFKit/simone/issue/20-update-to-3.3

Update to PSPDFKit 3.3.0