Use std::move in more places

Plus various code simplifications

Change-Id: I19805e4a635e4c74afaff68f9d8968475217ec6e
diff --git a/src/data.cpp b/src/data.cpp
index 090b82d..169d99c 100644
--- a/src/data.cpp
+++ b/src/data.cpp
@@ -263,10 +263,10 @@
 }
 
 Data&
-Data::setContent(const ConstBufferPtr& value)
+Data::setContent(ConstBufferPtr value)
 {
   resetWire();
-  m_content = Block(tlv::Content, value);
+  m_content = Block(tlv::Content, std::move(value));
   return *this;
 }