新版本powerlog2.5，主要改动：
printf("Powerlog Version 2.5\n");

Makefile:
MYSQL = -L/usr/lib64/mysql -lmysqlclient

temperature.c:
UART_Receive(buffer, 4);

UART.h:
int UART_Receive(unsigned char *buf, int len);

UART.c:
int UART_Receive(unsigned char *buf, int len)
{
    int n, cnt;
    memset(buf, 0, len);
    for (cnt = 0; cnt < len; cnt += n)
    {
        n = read(UART_id, buf + cnt, len - cnt);
        if (n == 0)
            break;
    }
    return cnt;
}