Pid file

[steven6282]

Adds pid file (m_server.pid) locking. Shell script on pi will need to be updated with pid file location.

fixes #8

Anyone working on windows, fcntl library doesn't exist for windows. There is a file in .gitignore fcntl.py create it and add this to it for the code to get it to run on windows (without actually locking the pid file).

LOCK_EX = 0
LOCK_NB = 0

def fcntl(fd, op, arg=0):
    return 0
        
def ioctl(fd, op, arg=0, mutable_flag=True):
    if mutable_flag:
        return 0
    else:
        return ""
    
def flock(fd, op):
    return
        
def lockf(fd, operation, length=0, start=0, whence=0):
    return