Convert tree to using univalue. Eliminate all json_spirit uses.

src/wallet/rpcdump.cpp

@@ -19,7 +19,7 @@
 #include <boost/algorithm/string.hpp>
 #include <boost/date_time/posix_time/posix_time.hpp>
 
-#include "json/json_spirit_value.h"
+#include "json_spirit_wrapper.h"
 
 using namespace json_spirit;
 using namespace std;
@@ -130,7 +130,7 @@ Value importprivkey(const Array& params, bool fHelp)
 
         // Don't throw error in case a key is already there
         if (pwalletMain->HaveKey(vchAddress))
-            return Value::null;
+            return NullUniValue;
 
         pwalletMain->mapKeyMetadata[vchAddress].nCreateTime = 1;
 
@@ -145,7 +145,7 @@ Value importprivkey(const Array& params, bool fHelp)
         }
     }
 
-    return Value::null;
+    return NullUniValue;
 }
 
 Value importaddress(const Array& params, bool fHelp)
@@ -204,7 +204,7 @@ Value importaddress(const Array& params, bool fHelp)
 
         // Don't throw error in case an address is already there
         if (pwalletMain->HaveWatchOnly(script))
-            return Value::null;
+            return NullUniValue;
 
         pwalletMain->MarkDirty();
 
@@ -218,7 +218,7 @@ Value importaddress(const Array& params, bool fHelp)
         }
     }
 
-    return Value::null;
+    return NullUniValue;
 }
 
 Value z_importwallet(const Array& params, bool fHelp)
@@ -378,7 +378,7 @@ Value importwallet_impl(const Array& params, bool fHelp, bool fImportZKeys)
     if (!fGood)
         throw JSONRPCError(RPC_WALLET_ERROR, "Error adding some keys to wallet");
 
-    return Value::null;
+    return NullUniValue;
 }
 
 Value dumpprivkey(const Array& params, bool fHelp)