Modernize Android build system, bump dependencies

Summary:
- Build against Android SDK 26
- Upgrade to Gradle 4
- Upgrade to Android Plugin 3.0, adjust dependency management accordingly
- Upgrade Maven deployment plugin

Reviewed By: emilsjolander

Differential Revision: D6272007

fbshipit-source-id: b198b4c8e1a94e2ee031ad26193fdfdf5b52adf1

android/build.gradle

@@ -22,7 +22,7 @@ android {
 }
 
 dependencies {
-    compile project(':yoga')
+    api project(':yoga')
 }
 
 task sourcesJar(type: Jar) {