proper imports;

--- a/src/Pure/Tools/ci_profile.scala	Wed Oct 05 14:15:54 2016 +0200
+++ b/src/Pure/Tools/ci_profile.scala	Wed Oct 05 14:34:42 2016 +0200
@@ -7,7 +7,7 @@
 package isabelle
 
 
-import java.time._
+import java.time.{Instant, ZoneId}
 import java.time.format.DateTimeFormatter
 import java.util.{Properties => JProperties}