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/dbus_utils.h

diff --git a/buffet/dbus_utils.h b/buffet/dbus_utils.h
index cc25844..6314531 100644
--- a/buffet/dbus_utils.h
+++ b/buffet/dbus_utils.h
@@ -21,7 +21,7 @@
                                            const std::string& message);
 
 scoped_ptr<dbus::Response> GetDBusError(dbus::MethodCall* method_call,
-                                        const chromeos::Error* error);
+                                        const Error* error);
 
 
 dbus::ExportedObject::MethodCallCallback GetExportableDBusMethod(