Update card highlight style

Out with orange, in with blue and gray (on >= 4.4).

res/drawable/clickable_card.xml

@@ -1,6 +1,10 @@
 <?xml version="1.0" encoding="utf-8"?>
 <selector xmlns:android="http://schemas.android.com/apk/res/android">
-    <item android:drawable="@android:drawable/list_selector_background"
-          android:state_pressed="true" />
+    <item android:state_pressed="true">
+        <shape>
+            <solid android:color="@color/card_background_active" />
+        </shape>
+        <bitmap android:src="@drawable/card" />
+    </item>
     <item android:drawable="@drawable/card" />
 </selector>

res/values-v19/colors.xml

@@ -0,0 +1,4 @@
+<?xml version="1.0" encoding="utf-8"?>
+<resources>
+    <color name="card_background_active">#99bebebe</color>
+</resources>

res/values/colors.xml

@@ -11,4 +11,6 @@
 
     <color name="textsecure_holo_blue_light">#ff33b5e5</color>
 
+    <color name="card_background_active">#9933b5e5</color>
+
 </resources>