Tutorial app

Summary:
A very basic app with a scrolling list backed by a static data source. It also covers two bases that we hadn't before: Sections and Kotlin; the latter being the better choice for a modern Android tutorial anyway.

Missing right now: BUCK support (likely not going to come anytime soon due to the kapt limitations), the actual Flipper plugin integration (that's up next).

Reviewed By: jknoxville

Differential Revision: D15166195

fbshipit-source-id: 3cfaa1d243548279cabc4f244c13363f1bcaa36c

settings.gradle

@@ -13,6 +13,7 @@ include ':fbjni'
 include ':easywsclient'
 include ':sonarcpp'
 include ':sample'
+include ':tutorial'
 include ':doubleconversion'
 include ':glog'
 include ':libevent'
@@ -24,6 +25,7 @@ project(':fbjni').projectDir = file('libs/fbjni')
 project(':easywsclient').projectDir = file('libs/easywsclient')
 project(':sonarcpp').projectDir = file('xplat')
 project(':sample').projectDir = file('android/sample')
+project(':tutorial').projectDir = file('android/tutorial')
 project(':android').projectDir = file('android')
 project(':doubleconversion').projectDir = file('android/third-party/external/double-conversion/')
 project(':glog').projectDir = file('android/third-party/external/glog/')