Add category support

Extracted from 93cd26be1febe7f15783b616883d30c456237866 in https://github.com/ChinaXing/HiD
Add plugin support.

Extracted from 93cd26be1febe7f15783b616883d30c456237866 in https://github.com/ChinaXing/HiD
Add tag support.

Extracted from 93cd26be1febe7f15783b616883d30c456237866 in https://github.com/ChinaXing/HiD
whitespace tweaks

Extracted from 93cd26be1febe7f15783b616883d30c456237866 in https://github.com/ChinaXing/HiD
Various UTF-8 fixes

Extracted from 93cd26be1febe7f15783b616883d30c456237866 in https://github.com/ChinaXing/HiD
Pass 'hid' to new Post object.

Not sure this is needed but including it for the moment...

Extracted from 93cd26be1febe7f15783b616883d30c456237866 in https://github.com/ChinaXing/HiD
Complete plugins support.

Extracted from 52c7c856bfa33c6029a923b288e53b12810118fd in https://github.com/ChinaXing/HiD
Export tags and categories to page

Extracted from 556a1531cfb6169007fc96995c6c5661473bc695 in https://github.com/ChinaXing/HiD
Add auto_reflesh attribute to server, a la jekyll

Extracted from 556a1531cfb6169007fc96995c6c5661473bc695 in https://github.com/ChinaXing/HiD
Update Changes and add CONTRIBUTORS section