Update custom timestamp format

Signed-off-by: Youhei SASAKI <uwabami@gfd-dennou.org>
rename index.org -> 00index.org for jekyll articles

Signed-off-by: Youhei SASAKI <uwabami@gfd-dennou.org>
Update org-mode and jekyll settings

Signed-off-by: Youhei SASAKI <uwabami@gfd-dennou.org>
Update timepstamp settings

Signed-off-by: Youhei SASAKI <uwabami@gfd-dennou.org>