Update the README with up-to-date Swift versions and Installation Instructions.
@kuyazee @AliSoftware #95

Set APPLICATION_EXTENSION_API_ONLY build setting on built frameworks.
@AliSoftware #98 @nahung89 #88

Update tools used by the project (Xcode, CocoaPods, CI, Carthage).
Also SPM builds are now tested by CI.
@AliSoftware #97