Update OWNERS to be more specific

Still to do ... media/OWNERS

Test: Gerrit works as expected
Change-Id: I2645175569b579764d0298641287e56bfabeab9f
diff --git a/include/common_time/OWNERS b/include/common_time/OWNERS
new file mode 100644
index 0000000..f9cb567
--- /dev/null
+++ b/include/common_time/OWNERS
@@ -0,0 +1 @@
+gkasten@google.com