Revert "Move `node_modules` and `ruby gems` to the compilers that use them."

This reverts commit f15e92a7bd68a3ce1ba6edab69b60ff37da73794.
Only render `jade` and `html` file.
Move some files around, and add template for compiler and fileType.
change to require lib inside the compile function
Merge branch 'feature/make-compilers-modular' of https://github.com/oklai/koala into feature/make-compilers-modular
Make compilers lazily `require` `child_process` module for `exec`.
Fix a bug that prevented the `navlist` from showing.
Add a way to install compiler packages.
Add basic support for update detection for compilers.
Add file types packages, with basic support for update detection.
Add extension packages, with basic support for update detection.
Extensions are the combination of:
* file types
* compilers
* locales
Minor code enhancements and clean-up.