remove pandoc templates

- kramdown is more suitable for blog post preview, since the jekyll
  itself is using kramdown right now.
- for writing simple/long report, latex is still unbeatable, and
  Latexian is a good companion.
remove terminal-notifier wrapper
remove script to compile markdown to pdf
remove pdb wrapper
simplify mathjax config

there is no need to specify math delimiter anymore, kramdown will take
care of that.
vim markdown highlight math
add alias gs
deal with edge case of dirs
add ruby conf