Add active-users post
Merge pull request #2 from kirankulkarni/active_users

Add active-users post
Fixup filename and metadata
Fix README
Fixup
Handle Ruby deps via Bundler, update README
Fix SSL issue with mathjax - make protocol independent
Use copy color on Mathjax render,

    * fix mathjax cdn url (rackcdn is https only)
    * fix indent in post
Change backtick to latex in active-users