Update icon in main.js

Should fix #143
Fix JS errors
Merge pull request #151 from juhasch/codefolding

Fix JS errors for 2.x
Fix runtools for 2.x and use relative CSS import
Remove unused initialization
Merge pull request #158 from juhasch/runtools_2x

Fix runtools for 2.x and use relative CSS import
Sync with upstream/2.x
Merge branch '2.x' of https://github.com/juhasch/IPython-notebook-extensions into 2.x