Changed style of encoding definition

Similar to https://github.com/gae-init/gae-init-upload/commit/137184c255cd95bd1be4d6371f8bec94b7a826ee changed to using `# coding: utf-8` on top of .py files. Also added empty line in `import` area of `main/serve.py` as `urllib` is batteries included Python (see https://docs.python.org/2/library/urllib.html) while the other imports are GAE specific (following `gae-init` coding conventions for `import` sections).