Improve external representation and object mapping

• If the response type has payloadPath, the responded body data should be handled as buffer not external representation.
• More robust mapping process between external representation and object. It's necessary for successfully decoding with Swift's Decoder
  • Convert the value in XML to JSON native type if the value is meaningful for JSON. (e.g, "null" => null, "3.1" => Double: 3.1)
  • Convert the header value to number if it can cast Double. (e.g "1" => Int: 1, "1.1" => Double: 1.1)

1.0.4: Merge pull request #13 from noppoMan/add-description

add descriptions to TimeStamp type

1.0.3: Merge pull request #12 from noppoMan/add-timestamp-type

add TimeStamp type to handle timestamp value in response

1.0.2: Merge pull request #10 from noppoMan/kludgey-decimal-cast

kludgey decimal cast for Linux platforms

1.0.1: Merge pull request #9 from noppoMan/linux-numeric-cast

fix numeric cast failed on linux

Swift 4 and 3.2 supporting

• Start to support Swift 4 and 3.2
• No compatibility with Swift 3.1

0.2.5: Merge pull request #7 from noppoMan/swift4

Update files to Swift 4 layout

0.2.4: Merge pull request #6 from noppoMan/meta-data-service

add MetaDataService to auto retrieve instance role credentials

0.2.3: Merge pull request #5 from noppoMan/flat-dictionary

add serializeToFlatDictionary to create valid query string for services that use query service protocol

0.2.2: Merge pull request #4 from noppoMan/noppoMan-patch-1

remove non allowed characters