FIX codemaster css rendering problem

* Chrome has a weird bug covering the first line
* seems that `.CodeMirror-scroll` is the cause
	* mainly `margin-bottom` and `padding-bottom`
	* used for hiding the scrollbar in CodeMirror
* since ecogwiki always use auto-resize
	* set `margin` and `padding` to 0
Merge pull request #3 from jangxyz/FIX-code-master-css

FIX codemaster css rendering problem