Pwittchen Swipe Versions Save

• added possibility to consume touch events -> issue #27 -> PR #28
• added abstract class SimpleSwipeListener implementing SwipeListener interface, which allows to implement several touch events without being forced to implement all of them -> PR #28
• bumped RxJava2.x -> 2.1.9
• bumped Truth -> 0.39
• bumped Kotlin version -> 1.2.20

• migrated library to RxJava2.x as a separate artifact on a separate Git branch
• removed master branch from the repo
• updated project dependencies
• updated Gradle to 3.x
• added Retrolambda to sample Java app

• migrated library to RxJava2.x as a separate artifact on a separate Git branch
• removed master branch from the repo
• updated project dependencies
• updated Gradle to 3.x
• added Retrolambda to sample Java app

• updated project dependencies
• updated Gradle configuration
• updated sample apps
• renamed com.github.pwittchen.swipe.library.Swipe#addListener to com.github.pwittchen.swipe.library.Swipe#setListener - issue #14
• added Swipe(int swipingThreshold, int swipedThreshold) constructor, which allows to configure swiping and swiped threshold/sensitivity - fixes #17

First release of the library.