Updates Carfile, Package.swift, and Podspec to use Swinject 2.8.1
Updates the documentation
Raises the minimum supported version of iOS platform to 9.0 (to match Swinject's)
Uses Carthage and CocoaPods optimistic operator (~>) to specify the Swinject dependency, this way we can benefit from Swinject hotfixes without needing to change SwinjectAutoregistration podspec.
This PR: