buffet: Remove 'chromeos' namespace and move everything to buffet NS

As discussed, moved all the classes out of chromeos namespace into
'buffet.

Also fixed a number of cpplint's warnings.

BUG=None
TEST=Everything still compiles and unit tests succeed.

Change-Id: Ide864acb2504627404966727f66d353af60e531d
Reviewed-on: https://chromium-review.googlesource.com/198971
Reviewed-by: Christopher Wiley <wiley@chromium.org>
Commit-Queue: Alex Vakulenko <avakulenko@chromium.org>
Tested-by: Alex Vakulenko <avakulenko@chromium.org>

buffet/http_transport.h

diff --git a/buffet/http_transport.h b/buffet/http_transport.h
index e9ea581..e26ee77 100644
--- a/buffet/http_transport.h
+++ b/buffet/http_transport.h
@@ -14,7 +14,7 @@
 
 #include "buffet/error.h"
 
-namespace chromeos {
+namespace buffet {
 namespace http {
 
 typedef std::vector<std::pair<std::string, std::string>> HeaderList;
@@ -49,6 +49,6 @@
 };
 
 }  // namespace http
-}  // namespace chromeos
+}  // namespace buffet
 
 #endif  // BUFFET_HTTP_TRANSPORT_H_