azkaban-memoizeit

diff --git a/.classpath b/.classpath
index c81935d..f3617fb 100644
--- a/.classpath
+++ b/.classpath
@@ -17,6 +17,7 @@
 	<classpathentry kind="lib" path="lib/slf4j-api-1.6.1.jar"/>
 	<classpathentry kind="lib" path="lib/slf4j-log4j12-1.6.4.jar"/>
 	<classpathentry kind="lib" path="lib/velocity-1.7.jar"/>
+	<classpathentry kind="lib" path="lib/velocity-tools-2.0.jar"/>
 	<classpathentry kind="con" path="org.eclipse.jdt.junit.JUNIT_CONTAINER/4"/>
 	<classpathentry kind="lib" path="lib/httpclient-4.2.1.jar"/>
 	<classpathentry kind="lib" path="lib/commons-io-2.4.jar"/>

diff --git a/lib/velocity-tools-2.0.jar b/lib/velocity-tools-2.0.jar
new file mode 100644
index 0000000..beb7434
Binary files /dev/null and b/lib/velocity-tools-2.0.jar differ

diff --git a/src/java/azkaban/utils/Utils.java b/src/java/azkaban/utils/Utils.java
index 257508a..44edfaa 100644
--- a/src/java/azkaban/utils/Utils.java
+++ b/src/java/azkaban/utils/Utils.java
@@ -322,7 +322,7 @@ public class Utils {
 	public static ReadablePeriod parsePeriodString(String periodStr) {
 		ReadablePeriod period;
 		char periodUnit = periodStr.charAt(periodStr.length() - 1);
-		if (periodUnit == 'n') {
+		if (periodStr.equals("null") || periodUnit == 'n') {
 			return null;
 		}