get rid of some last bootstrapbutton references

OpenKeychain/src/main/res/layout/decrypt_activity.xml

@@ -1,6 +1,5 @@
 <?xml version="1.0" encoding="utf-8"?>
 <android.support.v4.widget.FixedDrawerLayout xmlns:android="http://schemas.android.com/apk/res/android"
-    xmlns:bootstrapbutton="http://schemas.android.com/apk/res-auto"
     android:id="@+id/drawer_layout"
     android:layout_width="match_parent"
     android:layout_height="match_parent">
@@ -9,4 +8,4 @@
 
     <include layout="@layout/drawer_list" />
 
-</android.support.v4.widget.FixedDrawerLayout>
+</android.support.v4.widget.FixedDrawerLayout>

OpenKeychain/src/main/res/layout/decrypt_message_fragment.xml

@@ -1,6 +1,5 @@
 <?xml version="1.0" encoding="utf-8"?>
 <ScrollView xmlns:android="http://schemas.android.com/apk/res/android"
-    xmlns:bootstrapbutton="http://schemas.android.com/apk/res-auto"
     android:layout_width="match_parent"
     android:layout_height="match_parent"
     android:fillViewport="true">