fix problem with Android 4.x storage type selection

src/ZlibAndroid/ZlibAndroid.csproj

@@ -1,4 +1,4 @@
-<?xml version="1.0" encoding="utf-8"?>
+<?xml version="1.0" encoding="utf-8"?>
 <Project DefaultTargets="Build" ToolsVersion="4.0" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
   <PropertyGroup>
     <Configuration Condition=" '$(Configuration)' == '' ">Debug</Configuration>

src/keepass2android/Resources/drawable/storagetype_grid_bg.xml

@@ -3,7 +3,7 @@
 	<item >
 		<shape android:shape="rectangle"  >
 			<corners android:radius="6dip" />
-			<solid android:color="?activityBackgroundColor" />
+			<solid android:color="#fff" />
 		</shape>
 	</item>
 </selector>