Revert "Removes summary from legs property"

This adds the summary back to the RouteLeg, it now depends on if
`steps=true`.
This reverts commit eaf9993dd9.

src/engine/api/json_factory.cpp

@@ -194,6 +194,7 @@ util::json::Object makeRouteLeg(guidance::RouteLeg leg, util::json::Array steps)
     util::json::Object route_leg;
     route_leg.values["distance"] = std::round(leg.distance * 10) / 10.;
     route_leg.values["duration"] = std::round(leg.duration * 10) / 10.;
+    route_leg.values["summary"] = std::move(leg.summary);
     route_leg.values["steps"] = std::move(steps);
     return route_leg;
 }