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/sec-tpm-osx.cpp b/src/security/sec-tpm-osx.cpp
index d06cefe..fd21439 100644
--- a/src/security/sec-tpm-osx.cpp
+++ b/src/security/sec-tpm-osx.cpp
@@ -28,12 +28,14 @@
 
 namespace ndn {
 
-class SecTpmOsx::Impl {
+class SecTpmOsx::Impl
+{
 public:
   Impl()
     : m_passwordSet(false)
     , m_inTerminal(false)
-  {}
+  {
+  }
 
   /**
    * @brief Convert NDN name of a key to internal name of the key.