exceptions: Make Tlv::Error a base class for all packet-processing exceptions

This commit also includes a number of code style fixes.

Change-Id: I44f83915e733b43d5f43b4266902c8262e928d91
Refs: #1528
diff --git a/src/security/validator.hpp b/src/security/validator.hpp
index 43ab01a..38a8db2 100644
--- a/src/security/validator.hpp
+++ b/src/security/validator.hpp
@@ -24,7 +24,8 @@
  *
  * The Validator class provides the interfaces for packet validation.
  */
-class Validator {
+class Validator
+{
 public:
   class Error : public std::runtime_error
   {