removed deprecated import, added scss-like args, fixed dest_dir creation issue

optparse is deprecated in 2.7 in favor of argparse. Swapped them out.

Changed the commandline args to be more like sass. e.g., sass --watch style.scss:style.css

Had a problem with recursively-created dest dirs. Fixed that.
```
$ ls -Ra dest/
dest/:
.  ..  about.html  dest  posts

dest/dest:
.  ..  dest  index.html

dest/dest/dest:
.  ..  404.html

dest/posts:
.  ..  name.html
```