Added 'extra-cflags','extra-libs' and 'package-dependencies' to config.json that zephir supports compile and link with external-libraries.

Signed-off-by: Rack Lin <racklin@gmail.com>
Fixes indent

Signed-off-by: Rack Lin <racklin@gmail.com>
Merge pull request #636 from racklin/pkgconfig

Added Zephir supports compile and link with external-libraries