Improve primary and backend editor

[ffiesta]

Hi,

After using wikidocs for some time, there are some improvements that can be made:

1. Using same editor to primary edition and to extended edition, because it's more easy to solve markdown parse errors

   Primary editor (OK) - Primary preview (Not OK) */** Extended editor (OK) - Extendend preview (OK)
   Primary editor (OK) - Primary preview (OK) */** Extended editor (OK) - Extendend preview (Not OK)

   Extended editor (OK) - Extendend preview (OK) */** Primary editor (OK) - Primary preview (Not OK)
   Extended editor (OK) - Extendend preview (Not OK) */** Primary editor (OK) - Primary preview (OK)

2. After this ww can start using some implement some advanced markdown features like columns (left and right), define standardization to images (show all images in specific size) instead some big and another small