Add pinned section listview library

OpenPGP-Keychain/project.properties

@@ -11,3 +11,4 @@
 target=android-19
 android.library.reference.1=../libraries/ActionBarSherlock
 android.library.reference.2=../libraries/HtmlTextView
+android.library.reference.3=../libraries/pinned-section-listview/library

README.md

@@ -221,6 +221,10 @@ Some parts (older parts and some libraries are Apache License v2, MIT X11 Licens
   http://code.google.com/p/zxing/  
   Apache License v2
   
+* pinned-section-listview    
+  https://github.com/beworker/pinned-section-listview  
+  Apache License v2
+
 
 ## Images
 * icon.svg