Fix race condition which can happen with multiple concurrent "launch"es - can end up with duplicate ToePools like before r7268, probably other problems

* CrawlJob.java
    launch() - synchronize this method - sort of a blunt fix but probably safest and shouldn't affect performance

engine/src/main/java/org/archive/crawler/framework/CrawlJob.java

@@ -397,7 +397,7 @@ public class CrawlJob implements Comparable<CrawlJob>, ApplicationListener<Appli
      * (Note the crawl may have been configured to start in a 'paused'
      * state.) 
      */
-    public void launch() {
+    public synchronized void launch() {
         if (isProfile()) {
             throw new IllegalArgumentException("Can't launch profile" + this);
         }