Conversion to Swift 5

- convert all targets to Swift 5
- bump .swift-version
- update podspec
- fix warnings

Armchair.podspec

@@ -22,12 +22,12 @@ Pod::Spec.new do |s|
   s.source                = { :git => 'https://github.com/UrbanApps/Armchair.git', :tag => s.version }
 
   s.license               = { :type => "MIT", :file => "LICENSE" }
-  
+
   s.source_files          = "Source/*.{h,swift}"
   s.resources             = "Localization/*.lproj"
   s.ios.deployment_target = '8.0'
   s.osx.deployment_target = '10.10'
   s.requires_arc          = true
-  s.swift_version         = '4.2'
+  s.swift_version         = '5.0'
 
 end