Add information about how to go in the Packages folder in Sublime Text 3

For more clear information about Sublime Text support, Issue [#7]
Fix README view size on GitHub

Image with the bug: http://f.cl.ly/items/1O1q1n2R1V3f0b182Z0F/bug.png
Merge branch 'add_sublime_3_instructions'

* add_sublime_3_instructions:
  Fix README view size on GitHub
  Add information about how to go in the Packages folder in Sublime Text 3