Deprecate GradientLimit?

[udaysagar2177]

GradientLimit is very similar to Gradient2Limit except for few minor things and looks like GradientLimit needs some fixes, such as:

-            estimatedLimit = Math.max(minLimit, queueSize);
+            estimatedLimit = Math.max(minLimit, Math.min(maxLimit, queueSize));
...
-        newLimit = Math.max(queueSize, Math.min(maxLimit, newLimit));
+        newLimit = Math.max(minLimit, Math.min(maxLimit, newLimit));

And those from this PR: #134.

With all these fixes, GradientLimit will be exactly equal to Gradient2Limit except for the probeInterval.