Swift 5 Support

[FabrizioBrancati]

This PR aims to add Swift 5 support:

• Update BFKit-Swift to Swift 5 (Xcode 10.2 beta 1)
• Remove all the warnings

[coveralls]

Pull Request Test Coverage Report for Build 1378

• 313 of 323 (96.9%) changed or added relevant lines in 37 files are covered.
• 60 unchanged lines in 8 files lost coverage.
• Overall coverage increased (+1.9%) to 87.789%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
Sources/BFKit/Apple/UIKit/UIColor+Extensions.swift	17	18	94.44%
Sources/BFKit/Apple/UIKit/UIImage+Extensions.swift	31	32	96.88%
Sources/BFKit/Apple/UIKit/UIScreen+Extensions.swift	5	7	71.43%
Sources/BFKit/Apple/UIKit/UIViewController+Extensions.swift	2	4	50.0%
Sources/BFKit/Apple/UIKit/UIWindow+Extensions.swift	2	6	33.33%

Files with Coverage Reduction	New Missed Lines	%
Sources/BFKit/Apple/BFKit/BFBiometrics.swift	1	68.0%
Sources/BFKit/Linux/Foundation/Date+Extensions.swift	1	95.56%
Sources/BFKit/Apple/UIKit/UIColor+Extensions.swift	2	82.8%
Sources/BFKit/Apple/UIKit/UIButton+Extensions.swift	2	93.1%
Sources/BFKit/Apple/UIKit/UIView+Extensions.swift	2	90.66%
Sources/BFKit/Apple/UIKit/UIViewController+Extensions.swift	2	20.0%
Sources/BFKit/Apple/UIKit/UIImage+Extensions.swift	11	83.5%
Sources/BFKit/Apple/UIKit/UIWindow+Extensions.swift	39	20.59%

Totals
Change from base Build 1366:	1.9%
Covered Lines:	2919
Relevant Lines:	3325

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💛 - Coveralls