Convert plain Makefile into cmake

The package can be configured with 4 different options:

-DWITH_REDIS=ON

Enable support for Redis DB

-DWITH_JSON=ON

Enable support for JSON based output

-DENABLE_DEVELOPMENT=ON

Enable all warnings and make them fatal

-DENABLE_HARDENING=ON

Compile and link with some hardening

Use the new system by creating a build directory and change into that.
And then call the following

cmake -DWITH_REDIS=OFF -DWITH_JSON=ON -DENABLE_DEVELOPMENT=ON -DENABLE_HARDENING=ON /path/to/source/dir/
make
make DESTDIR="/..." install

Signed-off-by: Justin Lecher <jlec@gentoo.org>

Merged by David Adrian
- Remove src/Makefile
- Updated .gitignore for CMake
Finish moving zmap to CMake

- Generalize libjson support in CMakeLists
- Remove zopt.h, zopt.c from the repository