Fix quickstart guide

- Fixes #15
Allow wrapped values to be null.
Add instruction for accessing nested object
Add instruction for calling set
Merge pull request #16 from abrkn/allow-null-value

Allow wrapped values to be null
Fix allow null logic to also allow undefined
Rename bower package to cortexjs
Bump bower version
Publish cortex as node module

- Fixes #13
Mention file system example demo
Update README.md
Fix README
Merge branch 'master' of https://github.com/mquan/cortex