Ignore modules from sys.path

It makes check-webkit-style gets wrong pylint.
Support tern

* http://ternjs.net/
* Requirements
 $ apt-get install nodejs, npm
 $ npm install acorn glob minimatch
In js2-mode, do code folding by <f5> rather than C-c C-f

I prefer to bind C-c C-f as gtags-find-file