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)

Here the prepended comma will be removed.

* Hello
** Goodbye
 *** Not a headline, but prepended comma still removed.
* I am a headline

Here the prepended comma is should not be removed.

{
  "one":   1
, "two":   2
, "three": 3
, "four":  4
}

Here the prepended comma is also removed

Emacs Org mode implementation also removes it.

text = <<TEXT
#+TITLE: Prepended comma world
* Hello world
More text here
TEXT

Here the prepended comma will be remove for the Hello world headline

,  ,* Hi
,  
,  ,* This will be appended a comma
* Hello world  
,  

Here the prepended comma will be removed

#+TITLE: "Hello world"

This will be rendered as normal

,,,,,,,,,,,,,,,,,*Hello world