Major revisions to app generator, add permission, samples sub-generator

I made new version generator for chromeapp. What new things is

- Revision chromeapp:app generator, legacy permission code removed
- permission sub-generator added
- google-chrome-samples sub-generator added
- `debug` task added for live reloading
- `build` task added for packaging
- coffee-script, compass task has been dropped from watch task in temporary

Please refer to new [readme.md](https://github.com/ragingwind/generator-chromeapp/blob/master/readme.md) for understanding

@addyosmani I was disabled to the coffee-script, compass tasks to reduce confusion of users for a while. I'll that tasks put into next version of the generator. But until now, I could not found the clear/good/nice way of using livereload with coffee-script and compass. as you know, 'webapp generator' can using intermediate path (.tmp) but chromeapp can't use it, all of generated files has be still under the source path. I'm not sure that would be ok. I'd like to get more digging to solve it.

If you have any ideas? please let me know.