Major change

Well, where to start explaning this... a few days ago I've seen this gem and noticed a few things I would like to do differently... these were mostly personal-taste changes and not so much improvements or bugfixes... things like using ruby-2.0, documentation with yard, and certain code changes relating json parsing...


I'm an amateur programmer (I dont do it professionaly), and have limited experience with git, and none with tests... even so, as I had no more pretension than to make some personal changes and better understand this gems code, Ive forked it and started to change it... At some point, my enthusiasm lead me to accumulate many changes without properly documenting and separating them with git branches... (well, my git branches are a real mess...). Also, I'm aware that I've break some "standards" like renaming files from my_class.rb to MyClass.rb ( but it seems a so much better fit)...


Nonetheless, I think the code changes are relevant, and they constitute an updated and working version of the previous code. 


Most notorious changes are:
  - 100% compatible with previous work
  - Bitstampede::BitstampPublicApi (all API methods implemented)
  - Bitstampede::BitstampPrivateApi (same methods as before)
  - documented Client methods using yard docs
  - all Client methods (both Public and Private) have working examples/* 
  - fixed net_http_persistent to reuse an already existing connection
  - 

The not-so-perfect sides:
  - my git mess: just see latest commit of branch "major_changes"
  - tests are not updated/created, I didn't touch them... and those are important

 
So I send you this pull request, for you to check the changes out (already warned about my git mess)
I code as a hobby, for pleasure - I'm not a professional, although it crosses my mind from time to time -  so I would love to hear some sincere feedback from you :)

Paulo