fix "static is not at beginning of declaration" warning
fix "passing argument 2 of calloc with different width due to prototype" warning

initialize all fields of the json_value_none
add Makefile
fix warnings for test.c

- delete unused variables
- compare same sign values with cast
- include required header
integrate terms 'passed' to 'pass' used as result of unit test
add test cases
modify format for print result of test case