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-config.cpp b/src/security/validator-config.cpp
index 77d3354..4b430ce 100644
--- a/src/security/validator-config.cpp
+++ b/src/security/validator-config.cpp
@@ -70,7 +70,7 @@
     {
       boost::property_tree::read_info(input, tree);
     }
-  catch (const boost::property_tree::info_parser_error& error)
+  catch (boost::property_tree::info_parser_error& error)
     {
       std::stringstream msg;
       msg << "Failed to parse configuration file";