Payment Protocol: X509-validated payment requests

Add support for a Payment Protocol to Bitcoin-Qt.

Payment messages are protocol-buffer encoded and communicated over
http(s), so this adds a dependency on the Google protocol buffer
library, and requires Qt with OpenSSL support.

src/qt/test/test_main.cpp

@@ -1,16 +1,21 @@
-#include <QTest>
-#include <QObject>
-
-#include "uritests.h"
-
-// This is all you need to run all the tests
-int main(int argc, char *argv[])
-{
-    bool fInvalid = false;
-
-    URITests test1;
-    if (QTest::qExec(&test1) != 0)
-        fInvalid = true;
-
-    return fInvalid;
-}
+#include <QTest>
+#include <QObject>
+
+#include "uritests.h"
+#include "paymentservertests.h"
+
+// This is all you need to run all the tests
+int main(int argc, char *argv[])
+{
+    bool fInvalid = false;
+
+    URITests test1;
+    if (QTest::qExec(&test1) != 0)
+        fInvalid = true;
+
+    PaymentServerTests test2;
+    if (QTest::qExec(&test2) != 0)
+        fInvalid = true;
+
+    return fInvalid;
+}