increase the upper limit of the server invocation threshold in tests

Increase the upper limit of the server invocation threshold in tests because http get also uses HttpTransportClient.connect() method, thereby increasing the number of server invocations significantly during a test run.

src/test/java/com/salesforce/dataloader/process/ProcessTestBase.java

@@ -71,7 +71,7 @@
 public abstract class ProcessTestBase extends ConfigTestBase {
 
     private static Logger logger = LogManager.getLogger(ProcessTestBase.class);
-    private int serverApiInvocationThreshold = 100;
+    private int serverApiInvocationThreshold = 150;
 
     protected ProcessTestBase() {
         super(Collections.<String, String>emptyMap());