1. Call cli with explicit argv
When using debugging tools like `pydbg.py --some_arg idf.py -G Ninga
build`, those tools usually call the python script with sys.argv
modified to correct value. But if the cli is called with argv blank, the
cli will get the argv again, and finally get the original command line,
which is incorrect for debugging.
2. Encode the style unicode string back to ascii in menuconfig cmd
On Windows MSYS python2.7, the unicode string set in os.environ will
cause the subprocess creating to fail. All os.environ values should be
strings.
