Add util headers

None of the util files had headers.

internal/util-interface/src/main/java/xsbti/Logger.java

@@ -1,6 +1,10 @@
-/* sbt -- Simple Build Tool
- * Copyright 2009  Mark Harrah
+/*
+ * sbt
+ * Copyright 2011 - 2018, Lightbend, Inc.
+ * Copyright 2008 - 2010, Mark Harrah
+ * Licensed under Apache License 2.0 (see LICENSE)
  */
+
 package xsbti;
 
 import java.util.function.Supplier;

internal/util-interface/src/main/java/xsbti/Position.java

@@ -1,6 +1,10 @@
-/* sbt -- Simple Build Tool
- * Copyright 2008, 2009, 2010  Mark Harrah
+/*
+ * sbt
+ * Copyright 2011 - 2018, Lightbend, Inc.
+ * Copyright 2008 - 2010, Mark Harrah
+ * Licensed under Apache License 2.0 (see LICENSE)
  */
+
 package xsbti;
 
 import java.io.File;

internal/util-interface/src/main/java/xsbti/Problem.java

@@ -1,6 +1,10 @@
-/* sbt -- Simple Build Tool
- * Copyright 2008, 2009, 2010  Mark Harrah
+/*
+ * sbt
+ * Copyright 2011 - 2018, Lightbend, Inc.
+ * Copyright 2008 - 2010, Mark Harrah
+ * Licensed under Apache License 2.0 (see LICENSE)
  */
+
 package xsbti;
 
 import java.util.Optional;

internal/util-interface/src/main/java/xsbti/Severity.java

@@ -1,6 +1,10 @@
-/* sbt -- Simple Build Tool
- * Copyright 2008, 2009, 2010  Mark Harrah
+/*
+ * sbt
+ * Copyright 2011 - 2018, Lightbend, Inc.
+ * Copyright 2008 - 2010, Mark Harrah
+ * Licensed under Apache License 2.0 (see LICENSE)
  */
+
 package xsbti;
 
 public enum Severity

internal/util-interface/src/main/java/xsbti/T2.java

@@ -1,3 +1,10 @@
+/*
+ * sbt
+ * Copyright 2011 - 2018, Lightbend, Inc.
+ * Copyright 2008 - 2010, Mark Harrah
+ * Licensed under Apache License 2.0 (see LICENSE)
+ */
+
 package xsbti;
 
 /** Used to pass a pair of values. */