Add docopt to parse command line parameters
Make main.main() a classmethod of main.App
Add command line parameter to specify log folder
Remove isinstance(cls, object) checks

I believe we can be reasonably sure that wx classes are new style
classes. After all, they are using descriptors themselves. Furthermore,
recent versions of 'obsub' work with old style classes as well.

So just remove the check - it's only making everyone feel uncomfortable
when looking at the code.
Merge pull request #7 from coldfix/docopt

program options