add startup option for QEMU/mini2440 emulator

git-svn-id: https://rt-thread.googlecode.com/svn/trunk@353 bbd45198-f89e-11dd-88c7-29a3b14d5316

tools/run-mini2440-sdcard.bat

+start qemu-system-arm.exe -M mini2440 -kernel ..\bsp\mini2440\rtthread-mini2440.axf -show-cursor -sd SDCARD -serial telnet:127.0.0.1:1200,server
+