Update getting_started.rst

In the event they don't have python installed, this may help.
the extra space at the beginning will cause the line to appear as quoted text. Could you fix it. Below is a preview from the rendered version.
![screenshot 2014-07-05 23 37 41](https://cloud.githubusercontent.com/assets/305807/3487237/61a17fb0-046f-11e4-95d2-69274d3315c0.png)