[BACKPORT 2.5.3] Update sbt version to 0.13.18

Summary:
build fails on jenkins with 0.13.15

Original diff: https://phabricator.dev.yugabyte.com/D10937

Test Plan: Run sbt compile locally

Reviewers: mbautin, daniel

Reviewed By: daniel

Subscribers: yugaware, jenkins-bot

Differential Revision: https://phabricator.dev.yugabyte.com/D10938

Author: iSignal

managed/project/build.properties

@@ -1,4 +1,4 @@
 #Activator-generated Properties
 #Tue May 31 10:39:55 PDT 2016
 template.uuid=28ae6884-7b61-401c-834c-704789d1228a
-sbt.version=0.13.15
+sbt.version=0.13.18