Decreased the log level on a message relating to "purging" the cache.
In this case, no data is lost, its just a normal cleanup job.

Review at http://gwt-code-reviews.appspot.com/1447823

Review by: fabbott@google.com

git-svn-id: https://google-web-toolkit.googlecode.com/svn/trunk@10326 8db76d5a-ed1c-0410-87a9-c151d255dfc7
diff --git a/dev/core/src/com/google/gwt/dev/javac/PersistentUnitCache.java b/dev/core/src/com/google/gwt/dev/javac/PersistentUnitCache.java
index 17065dd..39bfe9c 100644
--- a/dev/core/src/com/google/gwt/dev/javac/PersistentUnitCache.java
+++ b/dev/core/src/com/google/gwt/dev/javac/PersistentUnitCache.java
@@ -420,7 +420,7 @@
       return;
     }
     if (logger.isLoggable(TreeLogger.INFO)) {
-      logger.log(TreeLogger.INFO, "Purging cache files from " + cacheDirectory);
+      logger.log(TreeLogger.TRACE, "Purging cache files from " + cacheDirectory);
     }
     for (File toDelete : filesToDelete) {
       if (!current.equals(toDelete)) {