Update config files

Author: oleghnidets

.swift-version

@@ -1,5 +1,5 @@
 language: objective-c # no matter that it is swift :)
-osx_image: xcode10
+osx_image: xcode10.2
 script:
     - xcodebuild -project TweeTextField.xcodeproj -scheme "TweeTextField-Sample" -sdk iphonesimulator -destination "platform=iOS Simulator,OS=10.1,name=iPhone 7" -configuration Debug -PBXBuildsContinueAfterErrors=0 ACTIVE_ARCH_ONLY=0 build
     - xcodebuild -project TweeTextField.xcodeproj -scheme "TweeTextField" -sdk iphonesimulator -configuration Debug -PBXBuildsContinueAfterErrors=0 ACTIVE_ARCH_ONLY=0 build

.travis.yml

@@ -14,6 +14,7 @@ This is lightweight library that provides different types of Text Fields based o
   s.author           = { 'Oleg Hnidets' => 'oleg.oleksan@gmail.com' }
   s.source           = { :git => 'https://github.com/oleghnidets/TweeTextField.git', :tag => s.version.to_s }
   s.ios.deployment_target = '10.0'
+  s.swift_version    = '5.0'
   s.requires_arc     = true 
   s.source_files     = 'Sources/*.swift'
   s.frameworks       = 'UIKit'