Helper class to send emails with attachments on Android
I'd change a few things to make your code cleaner.

Your send method does three different things: it extract the message from the context, it creates the intent and it finally launches the email app. What about introducing a Message class, a Message decodeMessage(Context context, String deviceName), and an Intent createIntent(Message message) methods?

getPackageInfo is definitely to arrow-shaped. I'd refactor it to separate the logic of creation of the package info string String formatPackageInfo(PackageInfo packageInfo) and the code to retrieve the PackageInfo instance.

private PackageInfo getPackageInfo(){
    String packageName = context.getPackageName();
    PackageManager manager = context.getPackageManager();
    if (manager == null)
        return null;
    try
    {
        return manager.getPackageInfo(packageName, 0);
    }
    catch (PackageManager.NameNotFoundException e)
    {
        Log.e(TAG, "Could not get package info", e);
    }
    return null;
}

private static String formatPackageInfo(PackageInfo packageInfo) {
        if(packageInfo == null)
            return "";
        return String.format("\n\n--\n[App: %s Version: %d/%s]",
                        packageName, info.versionCode, info.versionName);
}


In addAttachmentToIntent I'd probably move the declaration of dateFormat and of filename in the try block. You're not going to use them outside that scope so it could be a good idea to give them the smallest scope possible.