Tolerate Swift 5.1 (#44)

Tolerate Swift 5.1 (#44)

Fixes for Swift 4.2 on Linux (#43)

* Use same test as OSX, as issue IBM-Swift/SwiftRuntime#183 appears fixed in swift 4.2 on linux

* Use a String for the key in the json rather than an Int. Using an Int causes failure in Linux with swift 4.2. Surely all json keys are Strings anyway?

* Trap Int before Doubles before Bools in setPObjectHelper otherwise swift4.2 on linux can interpret Ints as Doubles and Bools as Ints

* Reinstate linux swift 4.2 build on travis

Tolerate Swift 5 (#42)

Rename Package@swift-4.swift to Package@Swift-4.swift (#41)

Merge pull request #39 from KyeMaloy97/issue.removeIncremental

Removed _incremental protocol from JSONIndex struct

Merge pull request #36 from IBM-Swift/swift-4

Swift 4

Merge pull request #36 from IBM-Swift/swift-4

Swift 4

Swift 4 support (#33)

Kitura/Kitura#1047 Swift 3.1 changes