Add crude locking to seats.c
add <pthread.h> to seats.c, add mutex and signal destroyers to thread_pool.c, fix various bugs to get the thing to compile
Fix included bug in  reserveSeat.html and add mutex unlocking calls to seats.c functions that have return ststatements in teh middle of functions to prevent blocking. Now works perfectly single threaded and includes the proper locks in seats.c
change threadpool = pool_create(0,0) to threadpool = pool_create(8,20). Multithreading seems to work now.
fix cancel function in reserveSeat.html. Note that python test scripts are currently returning error 400, but manual testing works fine
create new connfd for each connection to remove 400 status error. Now test case 2 passes, test case 1 has 3 fails, and test case 3 has 120 fails.