Add BitcoinApplication & RPCConsole tests

Add test coverage for Qt initialization code & basic RPC console functionality.

src/qt/main.cpp

@@ -0,0 +1,17 @@
+// Copyright (c) 2018 The Bitcoin Core developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#include <qt/bitcoin.h>
+
+#include <QCoreApplication>
+
+#include <functional>
+#include <string>
+
+/** Translate string to current locale using Qt. */
+extern const std::function<std::string(const char*)> G_TRANSLATION_FUN = [](const char* psz) {
+    return QCoreApplication::translate("bitcoin-core", psz).toStdString();
+};
+
+int main(int argc, char* argv[]) { return GuiMain(argc, argv); }