wic: use optparse instead of cmdln

wic: use optparse instead of cmdln

cmdln.py https://pypi.python.org/pypi/cmdln was used in
creator.py to parse image plugin options and arguments.

There is no need in such a sofisticated API to do this
simple task. Standard option parser optparse.OptionParser
can do it just fine.

Modified Creator class to work with option parser.
Removed cmdln.py from the wic codebase.

Signed-off-by: Ed Bartosh <ed.bartosh@linux.intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>