Add kotlin-android-extensions to gradle
Add kotlin-android-extensions to gradle

 - We can use kotlin android extension so that we will not have to use ButterKnifes to bind views
 https://kotlinlang.org/docs/tutorials/android-plugin.html

Change-Id: Idd227a82674721f92dbeede18b4606f8077a2a4b

dbrant/apps-android-wikipedia,dbrant/apps-android-wikipedia,dbrant/apps-android-wikipedia,wikimedia/apps-android-wikipedia,wikimedia/apps-android-wikipedia,dbrant/apps-android-wikipedia,dbrant/apps-android-wikipedia,wikimedia/apps-android-wikipedia,wikimedia/apps-android-wikipedia