* Removing the prepended comma from Org mode example blocks

As mentioned in <http://orgmode.org/manual/Literal-examples.html>,
when at the beginning of the line there is either ",*" or ",#+"
this prepended comma should be removed before parsing.

(Fixes <https://github.com/bdewey/org-ruby/issues/50>)

** DONE Here the prepended comma will be removed.

#+begin_example org
  ,* Hello
  ,** Goodbye
  , *** Not a headline, but prepended comma still removed.
  ,* I am a headline
#+end_example

** DONE Here the prepended comma is should not be removed.

#+begin_example js
  {
    "one":   1
  , "two":   2
  , "three": 3
  , "four":  4
  }
#+end_example

** DONE Here the prepended comma is also removed
  Emacs Org mode implementation also removes it.

#+begin_example ruby
  text = <<TEXT
  ,#+TITLE: Prepended comma world
  ,* Hello world
  More text here
  TEXT
#+end_example

** DONE Here the prepended comma will be remove for the =Hello world= headline

#+begin_example org
  ,  ,* Hi
  ,  
  ,  ,* This will be appended a comma
  ,* Hello world  
  ,  
#+end_example

** DONE Here the prepended comma will be removed

#+begin_example org
  ,#+TITLE: "Hello world"
#+end_example

** DONE This will be rendered as normal

#+begin_example org
  ,,,,,,,,,,,,,,,,,*Hello world
#+end_example
