Add IPC functions based on shared memory

[yeonjjeong]

135

shmget(), shmat(), shmdt(), shmctl() in kernel/shm

sample app is located at application/shm shared memory is allocated by buddy algorithm. shared memory area is as following. (cf, include/knl/arch.h)

define IPC_START_OFFSET (APP_START_OFFSET + APP_SIZE)

define IPC_SIZE ((unsigned long) (512<<20)) // 512MB

[seungjunn]

Resolved #135