fix tokenize in aws credentials

Change-Id: Icae08e5f688da59ebe83ab79fcccb5171088c219
diff --git a/src/com/mirantis/mk/Aws.groovy b/src/com/mirantis/mk/Aws.groovy
index 742185e..a125717 100644
--- a/src/com/mirantis/mk/Aws.groovy
+++ b/src/com/mirantis/mk/Aws.groovy
@@ -25,7 +25,7 @@
 
     if (credentials.contains(':')) {
         // we have key and secret in string (delimited by :)
-        creds = credentials.tokenized(':')
+        creds = credentials.tokenize(':')
         username = creds[0]
         password = creds[0]
     } else {