Swift 4.2 version bump, pod spec cleanup and some file move around

bump version

Updated tests and support for swift 4.2

Change emoji fetch data logic

nit

Add resources to podspec

EmojiGroup iterable by conforming to Swift 4.2's CaseIterable. Added further tests for EmojiLookup and added support for code coverage report through Travis / codecoverage.io

Remove build entry for iPhone 4S from travis

Changed project build settings runtime path and deployment target of project to 8.0 (iOS)

Fixed travis version for example app to only build on iOS 11.2

Updated travis build script

Added JAZZY docs and updated README

Updated travis environment to support iOS 11.2 and xcode image version 9.2

Modified tests to generalize to older OS versions

Fixed tests