Bumped manifest to 4.902

<?xml version="1.0" encoding="utf-8"?>

<manifest

    xmlns:android="http://schemas.android.com/apk/res/android"

    android:versionCode="21004"

    android:versionName="4.901" package="com.fsck.k9"

    android:versionCode="21005"

    android:versionName="4.902" package="com.fsck.k9"

    >

    <uses-sdk

       android:minSdkVersion="15"