reestructure gradle config so modules can implement a base configuration

core.gradle

@@ -0,0 +1,29 @@
+apply from: '../versions.gradle'
+apply plugin: 'com.android.library'
+apply plugin: 'kotlin-android'
+apply plugin: 'kotlin-android-extensions'
+apply plugin: 'kotlin-kapt'
+
+android {
+    compileSdkVersion build_versions.target_sdk
+    buildToolsVersion build_versions.build_tools
+
+    defaultConfig {
+        minSdkVersion build_versions.min_sdk
+        targetSdkVersion build_versions.target_sdk
+        testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
+    }
+
+    compileOptions {
+        sourceCompatibility JavaVersion.VERSION_1_8
+        targetCompatibility JavaVersion.VERSION_1_8
+    }
+
+    testOptions {
+        unitTests.returnDefaultValues = true
+    }
+
+    lintOptions {
+        abortOnError false
+    }
+}