Metadata: fixed parsing of scaling factors

- Default C++ to_string implementation only supplies 6 decimal digits of
accuracy, truncating very small scaling factors
- Now using string streams

common/include/metadatastore.h

@@ -37,6 +37,7 @@
 #include <boost/property_tree/json_parser.hpp>
 #include <boost/algorithm/string/trim.hpp>
 #include <boost/algorithm/string.hpp>
+#include <sstream>
 #include "globalconfiguration.h"
 
 using namespace std;
@@ -196,6 +197,8 @@ protected:
     
     // Dumps the contents of "s" in "config"
     void _dumpPTREE(boost::property_tree::ptree& config) const {
+        std::ostringstream scaleStream;
+        scaleStream << this->scale;
         config.clear();
         config.push_back(boost::property_tree::ptree::value_type("isVirtual", boost::property_tree::ptree(this->isVirtual ? "true" : "false")));
         config.push_back(boost::property_tree::ptree::value_type("monotonic", boost::property_tree::ptree(this->monotonic ? "true" : "false")));
@@ -203,7 +206,7 @@ protected:
         config.push_back(boost::property_tree::ptree::value_type("unit", boost::property_tree::ptree(this->unit)));
         config.push_back(boost::property_tree::ptree::value_type("publicName", boost::property_tree::ptree(this->publicName)));
         config.push_back(boost::property_tree::ptree::value_type("pattern", boost::property_tree::ptree(this->pattern)));
-        config.push_back(boost::property_tree::ptree::value_type("scale", boost::property_tree::ptree(to_string(this->scale))));
+        config.push_back(boost::property_tree::ptree::value_type("scale", boost::property_tree::ptree(scaleStream.str())));
         config.push_back(boost::property_tree::ptree::value_type("interval", boost::property_tree::ptree(to_string(this->interval / 1000000))));
         config.push_back(boost::property_tree::ptree::value_type("ttl", boost::property_tree::ptree(to_string(this->ttl / 1000000))));
         config.push_back(boost::property_tree::ptree::value_type("operations", boost::property_tree::ptree(this->operations)));