objc support, viewcontroller as delegate

[punto2018]

Changelog:
-added support for objective c projects

• PassportScannerController can be used as delegate, without need to subclass it
• Added the processed image getter

• it is already merged with the version 4.0.1

[evermeer]

Could you solve the merge conflicts first?
Swift default casing for enums is lowercase. That was changed by me.
I also changed usePostProcessingFilters into showPostProcessingFilters so that it would be clearer for external users wat the parameter actually does.

[punto2018]

done!

[evermeer]

@punto2018 also done... Will publish to cocoapods later this evening