fine tunes and remove modernizr
replace underscore by lodash and reduce jshint err

Lo-Dash is employed and code is refined.
jshint options are edited per js file,
so that grunt jshint produces less errors.
replace cookie by localStorage to save app state

- Add a app model with localStorage to keep the app state.
- The url becomes /#ch/x/x.y.z instead of /#chx/x.y.z
- Some other minor teaks.
rearrange templates

chapter, section models, chapters collection, section view are removed.
Only use the toc object because it will be never altered.
remove calling of render during init in all views.

with some code cosmetics.
Code review and bug fixes