Logging & minor optimizations:

* Log load fee values (at debug) received from validations.
* Log remote and cluster fee values (at trace) when changed.
* Refactor JobQueue::isOverloaded to return sooner if overloaded.
* Refactor Transactor::checkFee to only compute fee if ledger is open.

src/ripple/core/impl/JobQueue.cpp

@@ -168,15 +168,13 @@ JobQueue::addLoadEvents(JobType t, int count, std::chrono::milliseconds elapsed)
 bool
 JobQueue::isOverloaded()
 {
-    int count = 0;
-
     for (auto& x : m_jobData)
     {
         if (x.second.load().isOver())
-            ++count;
+            return true;
     }
 
-    return count > 0;
+    return false;
 }
 
 Json::Value