Update CI config; minimum Swift version is now 5.0 (#59)

* Update CI config; minimum Swift version is now 5.0

* Update travis CI

* Update travis CI

* Updated README with pre-requisites

Merge pull request #56 from dannys42-contrib/master

Updated github org from IBM-Swift to Kitura

ci: Update to Swift 5.1

feat: Adopt swift-log (#47)

Support Swift 5 (#44)

Support Swift 5 (#41)

* Support Swift 5, drop Swift 3

Update LoggerAPI.podspec

Restore Swift 3.1.1 support (#27)

- and enable Travis

Merge pull request #20 from IBM-Swift/swift-4

Support Swift 4

Update to swift 3.1 and related changes