bump to 0.1.2
validate the parsed url to prevent invalid url string inputted by user.
test the url validator.
refine the description of site.route method.
change the sphinx theme to nature instead of kr.
refine the coding style in the document.
add a utility to convert unicode/bytes into bytes.
fix up the non-ascii path compatible problem.
add changelog and introduction into the document.
move user guide into a directory to prepare for extracting content.
extract contents of user guide into standalone pages.
Merge branch 'hotfix/0.1.2'