Update Makefile

Fixes for FreeBSD and clang++
Update jsonObject.cpp

NULL is not a valid integer.
Update main.cpp

Segmentation fault anyone? ;)
Update JHLib.h

clang complains otherwise
Update README.md

Added FreeBSD build notes
Merge pull request #1 from ofcaah/patch-4

Update JHLib.h
Merge pull request #2 from ofcaah/patch-2

Update jsonObject.cpp
Merge pull request #3 from ofcaah/patch-3

Update main.cpp
Merge pull request #1 from ofcaah/patch-1

FreeBSD build patch