added initial support for HKP key servers, allowing searching and key import

Update issue 9
Can search a key server now, touch a result to import the key. Still needs better error handling and some Intents to import keys based on key ID. Also still need key server preferences.

src/org/thialfihar/android/apg/KeyServer.java

@@ -0,0 +1,23 @@
+package org.thialfihar.android.apg;
+
+import java.io.IOException;
+import java.io.Serializable;
+import java.net.MalformedURLException;
+import java.util.Date;
+import java.util.List;
+import java.util.Vector;
+
+public abstract class KeyServer {
+    static public class KeyInfo implements Serializable {
+        private static final long serialVersionUID = -7797972113284992662L;
+        Vector<String> userIds;
+        String revoked;
+        Date date;
+        String fingerPrint;
+        long keyId;
+        int size;
+        String algorithm;
+    }
+    abstract List<KeyInfo> search(String query) throws MalformedURLException, IOException;
+    abstract String get(long keyId) throws MalformedURLException, IOException;
+}