Fix endianness detection on OS X

Signed-off-by: Sergey Nizovtsev <snizovtsev@gmail.com>
Fix default constructors of OXMTLV subclasses

Signed-off-by: Sergey Nizovtsev <snizovtsev@gmail.com>
Make OXMTLV getters constant
Optimize PacketIn getters
Remove one std::vector from of13::Match
Merge pull request #4 from ARCCN/master

Endianess and OXMTLV fixes