Enable Jetifier and AndroidX

Author: quinnjn

Diff for: .gitignore

@@ -1,5 +1,4 @@
 .gradle
-/gradle.properties
 /local.properties
 /.idea
 Gemfile.lock

Diff for: Drop-In/src/test/java/com/braintreepayments/api/dropin/view/AddCardViewUnitTest.java

@@ -1,6 +1,5 @@
 package com.braintreepayments.api.dropin.view;
 
-import android.app.Activity;
 import android.os.Bundle;
 import android.text.SpannableString;
 import android.view.View;

Diff for: gradle.properties

@@ -0,0 +1,5 @@
+# We need to enable Jetifier to switch our support libraries to AndroidX
+# We can remove this option after the following dependencies have AndrdoidX builds:
+# - com.google.android.gms:play-services-wallet
+android.enableJetifier=true
+android.useAndroidX=true