Nest all namespaces

The compiler supports this now.  We can type less going forward.
No functional changes.

Signed-off-by: Stephan Pleines <pleines.stephan@gmail.com>
Change-Id: I29d6fa4f9aacc0e381f1a7637294db0392466995
diff --git a/y2019/jevois/cobs_test.cc b/y2019/jevois/cobs_test.cc
index 303c4d3..61604ad 100644
--- a/y2019/jevois/cobs_test.cc
+++ b/y2019/jevois/cobs_test.cc
@@ -5,8 +5,7 @@
 
 #include "aos/testing/test_logging.h"
 
-namespace frc971 {
-namespace jevois {
+namespace frc971::jevois {
 
 // Tests the size conversions for some known, simple values.
 TEST(CobsMaxEncodedSizeTest, Simple) {
@@ -289,5 +288,4 @@
             packetizer.received_packet());
 }
 
-}  // namespace jevois
-}  // namespace frc971
+}  // namespace frc971::jevois