Add CODEOWNERS file. (#176)

* Add CODEOWNERS file.

* Fix path to be relative to root path.

Author: Bogdan Drutu

.github/CODEOWNERS

@@ -0,0 +1,13 @@
+# Code owners file.
+# This file controls who is tagged for review for any given pull request.
+
+# For anything not explicitly taken by someone else:
+*               @bogdandrutu
+
+# Owners per module:
+/builds/*       @rghetia
+/encodings/*    @bogdandrutu
+/metrics/*      @bogdandrutu
+/stats/*        @bogdandrutu
+/trace/*        @bogdandrutu
+/utils/*        @bogdandrutu