Add an empty model.py.
Move the options define and parse to the options.py.

It will simplify the structure so now we can remove the limit that
we cannot use the config in the global scope in one module.

We will alse remove the limit about the prepare of the context
object because the limit of options is removed.
Import modules in the blog/__init__.py and define the __all__.
Fix the bug of "No options such as 'options'".
Modified the path of config.py used by the options.py to debug.

'config.py' -> 'blog/config.py'
I think I should use a more pythonic method to solve it. Put the
config file into the /etc/ ?
Fix the bug that params' name wrong when create the TemplateLookup.
Remove the limit that we must prepare the context before using it.